I use classic shell as well and never had the problem. I tested them all and classic shell worked the best, all the others had some strange small freeze when it tries to update itself and draw the menus. Classic shell was the only one that didnt.
Maybe the best thing to do is uninstall it and then remove any left over settings that might be left in the registry or files by it and then install it again so that none of the old settings are there. Sounds like it just might be a messed up setting in classic shell and removing those settings and letting it start fresh might fix it.
Shane