The 'corrupt' archive in NeroBackItUp I don't think is a problem. More likely avast! just can't read it. Unless somebody with more knowledge tells you otherwise, ignore similar messages.
The 'decompression bomb' warning seems to be a DVD data file: safe to ignore. If one of those .VOB files is less than 10MB, you could email it to avast! mentioning it's a false positive, although they may well be more like 100MB+: far too big to email.
avscan.dll is an AntiVir file. Do you still have AntiVir installed? Two AV programs will conflict: if you're going to use avast!, you'll need to uninstall AntiVir.
What is the full location of this entry:
E:\Computer Stuff\...\avscan.dll?
There are two more in System Restore you can ignore: If you no longer have AntiVir, avscan.dll will get flushed out of System Restore as new restore points are created.