I will just post up some more information here:
When I try to startup Windows I just get a black screen and Windows won't start at all. I started the machine in safe mode and ran Malwarebytes' Anti-Malware, which found 20 infections. When it came to deleting the infections, the program prompted me to restart my machine. I am not at all convinced that the infections were got rid of. I restarted my machine as instructed, and Windows still wouldn't start. However, when I ran another scan in safe mode with Malwarebytes it told me my machine was clean.
I've since been back into safe mode, and ran Malwarebytes again, Spybot, Avast and AVG and none of them can find any infections at all. But my machine won't start. One time I ran Spybot in safe mode, it found 21 infections, but refused to delete three of them.
Here is the log from Malwarebytes when it detected numerous infections (which it doesn't detect any more):
Malwarebytes Anti-Malware (Trial) 1.60.1.1000
Malwarebytes : Free anti-malware, anti-virus and spyware removal download
Database version: v2012.04.06.09
Windows 7 Service Pack 1 x86 NTFS (Safe Mode/Networking)
Internet Explorer 9.0.8112.16421
Protection: Disabled
07/04/2012 02:47:31
mbam-log-2012-04-07 (02-47-31).txt
Scan type: Quick scan
Scan options enabled: Memory | Startup | Registry | File System | Heuristics/Extra | Heuristics/Shuriken | PUP | PUM
Scan options disabled: P2P
Objects scanned: 190882
Time elapsed: 4 minute(s), 17 second(s)
Memory Processes Detected: 0
(No malicious items detected)
Memory Modules Detected: 0
(No malicious items detected)
Registry Keys Detected: 15
HKCR\CLSID\{78F3A323-798E-4AEA-9A57-88F4B05FD5DD} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\TypeLib\{BB7256DD-EBA9-480B-8441-A00388C2BEC3} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\Interface\{3D782BB2-F2A5-11D3-BF4C-000000000000} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\MyNewsBarLauncher.IE5BarLauncherBHO.1 (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\MyNewsBarLauncher.IE5BarLauncherBHO (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{78F3A323-798E-4AEA-9A57-88F4B05FD5DD} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\Settings\{78F3A323-798E-4AEA-9A57-88F4B05FD5DD} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\Stats\{78F3A323-798E-4AEA-9A57-88F4B05FD5DD} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\PreApproved\{78F3A323-798E-4AEA-9A57-88F4B05FD5DD} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\CLSID\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\MyNewsBarLauncher.IE5BarLauncher.1 (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCR\MyNewsBarLauncher.IE5BarLauncher (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\Settings\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\Stats\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Quarantined and deleted successfully.
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Ext\PreApproved\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Quarantined and deleted successfully.
Registry Values Detected: 4
HKCU\SOFTWARE\Microsoft\Internet Explorer\Toolbar\WebBrowser|{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Data: ;áÃzÊ;XA³0öm»Áµ -> Quarantined and deleted successfully.
HKLM\SOFTWARE\Microsoft\Internet Explorer\Toolbar|{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Data: VShareTB -> Quarantined and deleted successfully.
HKCU\SOFTWARE\Microsoft\Internet Explorer\Toolbar\WebBrowser\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Data: -> Quarantined and deleted successfully.
HKLM\SOFTWARE\Microsoft\Internet Explorer\Toolbar\{7AC3E13B-3BCA-4158-B330-F66DBB03C1B5} (PUP.VShareRedir) -> Data: -> Quarantined and deleted successfully.
Registry Data Items Detected: 2
HKCU\SOFTWARE\Microsoft\Internet Explorer\Main|Start Page (Hijack.StartPage) -> Bad: (SearchCompletion Search) Good: (Google) -> Quarantined and repaired successfully.
HKLM\SOFTWARE\Microsoft\Internet Explorer\Main|Start Page (Hijack.StartPage) -> Bad: (SearchCompletion Search) Good: (Google) -> Quarantined and repaired successfully.
Folders Detected: 0
(No malicious items detected)
Files Detected: 3
C:\Program Files\vShare.tv plugin\BarLcher.dll (PUP.VShareRedir) -> Quarantined and deleted successfully.
C:\Users\Chris\Downloads\Retrogamer(2).exe (PUP.FunWebProducts) -> Quarantined and deleted successfully.
C:\Users\Chris\Downloads\Retrogamer.exe (PUP.FunWebProducts) -> Quarantined and deleted successfully.
(end)
Despite the fact that it states in this log that infections were successfully quarantined, when I start my machine again, Windows still won't run properly.
I have tried system restoring the PC to 25th March, this did no good at all. I've tried running every virus scanner and malware program that I can think of, none of them have done any good at all. With previous problems, I've always started the machine in safe mode, run a virus and spyware program, it's killed the infection, and that's that. This seems able to override safe mode, and also override the mechanisms in the anti-spyware and anti-virus programs that delete the infections.
I tried to run the OTL program suggested but it just freezes and won't run at all in safe mode. It is impossible to run anything in normal mode because the system either runs pitifully slowly or won't start at all.