Eset's NOD32 has as good a reputation as Kapersky so why not try their online scan? (after reading the Terms of Use);
http://www.eset.eu/online-scanner
If the scan runs OK that might suggest that there was a problem with Kapersky's servers when you tried their scan. If, on the other hand, you get similar problems with the Eset scan, that would suggest that the problem may be with your browser or its settings.