I did some full-scans and once in a blue-moon, results would be that "The system cannot find the path specified (3)": Here are the file names in question:
c:\program files\alwil software\avast5\defs\10052900\algo.dll
c:\program files\alwil software\avast5\defs\10052900\aswcmnbs.dll
c:\program files\alwil software\avast5\defs\10052900\aswcmnis.dll
c:\program files\alwil software\avast5\defs\10052900\aswcmnos.dll
c:\program files\alwil software\avast5\defs\10052900\aswengin.dll
c:\program files\alwil software\avast5\defs\10052900\aswscan.dll
Does anyone else get these?
Yes it is normal, if a little strange.
The VPS (virus definitions, defs) updates create new folders after a while older folders are removed in a house keeping exercise as they are effectively duplicates and quite large 50MB+ (see image of the latest VPS/defs folder). So it is possible that at the time you started scanning avast was also cleaning house and the old folder no longer exists.
Nothing to worry about, it happens on occasion. The main thing is that these are just files that can't be scanned and the reason why, not that they are infected/suspect.