Can file snapshots aid in detecting malware? I noticed certain programs have a feature that can have a 'snapshot' of a file from a certaim time and compare it to a more recent snapshot of the file. If one's system has a snapshot of a program when 'first' downloaded and  it can compare  this to the program 'as it is now' and if there are any changes this might indicate the file is corrupt and it could be marked for possible removal. So could this comparison feature be used to determine if a file is corrupt?
This is not likely to be very effective in practice.  Malware might corrupt the file before you were first able to take a snapshot... or, more realistically, it might corrupt the snapshot you have taken, so that the snapshot matches the current version of the file.  It is difficult to defend against that attack.

So, while your idea is not a bad one, it has significant limitations that might render it not terribly useful in practice.

This also assumes that the underlying file is one that should never change.  Of course, in practice, for any given file, there are valid circumstances when the file should be allowed to change.  So this means you'd need some way to recognize valid, legitimate changes to the file.  This starts to get a bit more complex to implement.

You might take a look at Tripwire, which is a system that does something like this -- except it keeps only a cryptographic hash of each monitored file, rather than a full copy of the file.