I managed to resolve the problem.
First of all, ensure that your user id (logging as Windows XP Pro from a domain controller) with Administrative privilage.
De-install all sothink product (I have got latest Sothink Glanda, DHTMLMenu, FlashVideo and SWF Quicker). Clean out the register setting in both HKEY_LOCAL_MACHINE and HKEY_CURRENT_USERS/Software/SourceTec.
Log out and log back in (ensure it is with Administrative privilage..... First install SlidingMenu, run those program and register it and copy slidingmenu.class then run again to check if everything is OK... Then do install DHTMLMenu then the rest...
Log out, ensure that your user id is changed back to 'Domain Users' and then everything is working perfectly (apart from other users on the same PC). The bug is still there for SlidingMenu - this need to be looking at it!!!
Hope this help with your investigation for re-coding!!!