Nothing about prefetching has anything to do with hiding files.
While stories like this appear, I think I'll remain paranoid:
Prior to deleting the prefetch folder the file did not appear in a search of the system32 folder.
it seems that the prefetch folder can actually load things even if they aren't being called anywhere
(See my previous posting for full links.)
I appreciate now that .pf files in Prefetch have the same name as the .exe file, e.g. MSBLAST.EXE-39813b24.pf, but it worries me that Sophos detected this file as a virus file: surely an AV works on content not just name?
Although I've seen no hard evidence that there is a risk from Prefetch other than malware files simply being in the folder, that alone seems to be a good enough reason to delete it along with all the temp and cache folders. Who's going to notice a slight slowdown in performance because prefetch is being rebuilt over the huge improvement in a crippled computer when malware is removed?
And the stories above do worry me.
Is it possible to say categorically that prefetch folder can't actually load things even if they aren't being called anywhere, and that the Prefetch file can't hide a file in the system folder?