There can be many reasons causing this problem. The OS software, Abacus software, and other softwares installed in the PC may have got corrupted. Unstable hardware could also cause this problem. Users may want to perform the followings:-
1. Re-install the Abacus Software and perform an emergency recovery on the Abacus system to see if it helps or not.
2. Remove unused application softwares from the PC. Update the OS to the latest service patch, and if needed, re-install the window OS.
3. If (1) and (2) fail, user may want to get a brand new / clean PC to have the Abacus software installed and try again.