STOP: 0x00000050 after installing Avast 2014.9.0.2011

[Qukis]

Hello,
 
This is really urgent for me...
I ran into a huge problem with Avast.
And I'm having trouble fixing it because my XP PC keeps throwing me a BSOD with error codes:
 
STOP: 0x00000050 and randomly (0xEE70F000; 0x8058AF5D; 0xEE92F000; 0xEE9B2000; 0x00000001; 0x00000000).
 
It happened after I installed Avast version 2014.9.0.2011 and rebooted.



The PC was clean of viruses, I had another Antivirus and Firewall before but decided to switch to Avast for speed.
Unluckily, I made a BIG mistake...
 
Windows loads but as soon as programs (Avast) start running I get an error and a blue screen with above mentioned error codes.
 
The problem is, I've tried F8 and it only shows me options for boot-up, like from which disc to boot, there is NO SAFE MODE option.



 
And now I'm stuck. I cannot start the PC and get rid of Avast.
 
Will someone please help me...
WHAT CAN I DO ?

[Eddy]

1)
The big mistake you made is likely not removing the old av completely before installing avast.

2)
If you do not get the "safe mode" option, you are either not pressing F8 at the right moment or the option has been hidden/removed by the one(s) who installed XP.

What av/software firewall did you had installed?
What exact version of avast do you have?

[thekochs]

If you do not get the "safe mode" option, you are either not pressing F8 at the right moment or the option has been hidden/removed by the one(s) who installed XP.

Perhaps this is not the issue as you said but there are instances where Safe Mode is all borked up.
Here is repair: http://www.majorgeeks.com/files/details/tweaking_com_repair_windows_safe_mode.html

However, for Qukis those not used to going into safe mode on their PC it can be tricky.
You need to wait for the POST (power on self test) of the BIOS to finish but BEFORE you see the Windows logo come up.
Typically the first thing you see is either the vendor (eg. DELL) logo come up on power where there is key option noted to going into boot options menu or BIOS.....never F8.  Right after this splash screen (this last maybe 2-4 seconds) you need to have hit F8....hit it many times...bang, bang, bang.  If you see Windows logo it did not take.