right-click scanner not working

[truefrogs]

i noticed a problem with avast yesterday, if i choose to scan any file using the right-click scanner, it will allways finish instantly ie; run time 0.00.00, this happens to small files less than 10MB and large files of many GB's in size
the only thing that does increase scan time is if there are lots of files in a folder i select to scan, ie; a folder with 100 10MB files will take much longer than a folder with 5 1GB files, which in turn would take longer than scanning a single 10GB file, this doesn't make sense and never used to be the case
this behavior also happens in the "scan computer/select folder to scan" option in the avast UI

i've already tried a repair install, but that didn't work, if anyone has any suggestions, i would appreciate the help

my setup:
32bit windows vista sp2
avast free antivirus ver. 6.0.1203
windows defender - on
UAC - on
malwarebytes free edition is also installed, but not actively running

[igor]

I'd say the scanning is just fast, nothing wrong going on.
What kind of huge files are you scanning?

[truefrogs]

mainly video files, i don't think avast is actually scanning them though, just going through the motions?
upto atleast last week it used to take avast between 20-25 seconds to scan a 1GB file, now it's 0.00.00 seconds, there must be something wrong there, i have all the settings for the right-click/ "scan from windows explorer" scanner maxed out, set to scan all files and packers, and NOT to use the persistent cache

[igor]

I don't think it happened last week, it's a bit longer already - but yes, the scanning of video files (for example) has been optimized, so it's very fast now - basically independent on the size of the file.

[truefrogs]

so is it normal now for avast to take less than a second to scan a video file of several gigabytes in size, even if avast has been told to scan the whole file?

[Lisandro]

so is it normal now for avast to take less than a second to scan a video file of several gigabytes in size, even if avast has been told to scan the whole file?

Yes. And it's perfectly safe.