Advast Free scans but never gets past 91%.

i have advast 2014 free on my Toshiba laptop running vista never had any problems in all the years I have used it except now when I try a scan it takes forever and goes to 91% but never gets past there… Thanks if you can help.

May help if you provided some details

Avast version 2014.?.?.??? (The current version is 2014.9.0.2011)
Avast type Free/one of the paid for versions
Vista 32 or 64
What type of scan - Quick/Full/Removable Media/Selected folders/Boot type Scan/Windows Explorer Scan.

Have you altered the default settings for the particular scan?.
When the scan reaches 91% what exactly happens, does the computer freeze, is there any messages, what do you need to do to get your computer back in normal operation?

If you look at the scan screen during the scan (for normal scans), you will see it shows the name of the file being processed (see attached screen shot). When the scan stops at 91%, is it always showing the same file name?.

If you have changed to avast from a different brand of AV, did you fully remove the old AV using the uninstall and clean up tool for that particular AV, rather than just using the uninstall via Control Panel.

If you have updated from a previous version of avast from within the old version program itself, then I would recommend downloading a copy of the latest version of Avast, and also a copy of AvastClear.exe, then:-
Uninstall your present version
Use AvastClear.exe to clean up
Reboot
Install the new version
Reboot

However before you do that, you could also try a repair.