Windows file system error 35 is a great help:
Undefined error code.
An error message can not be found for this error code.
So I don't know if this is a windows file system error and at the same time I don't know if it is in use by avast (they normally use higher numbers, 5 digit), so I'm in the dark here.
It seems to me that when BestSync checks to see if it needs to be backed up to the NAS, it opens the file for write permissions (or these paths look like writes to the backup as they are all there rather than the original file to be backed up). That causes avast to scan the file and it is this that is failing, avast can't scan the file and I don't know where the error 00000035 (35), which does look like a windows file error.
In setting an exclusion you would have to set it in the correct place, there are two lists, and it is the resident scanner Standard Shield, which I believe these scans are initiated by, so if they aren't excluded there, it won't work.
I think that your exclusion also won't work either. I don't know how you go about excluding a NAS address as there is no drive letter perhaps *\BestSync 2010\*\*.lnk the first * removes the worry about what drive letter (I think) then if they are all in the \BestSync 2010\ saves leaving a big hole in security, the second * if there are other folders after that and the *.lnk to exclude only those file types not everything. You would also have to look at other common folder locations and create an exclusion for those, like *\BestSync Deleted Files\*\*.lnk, etc.
