Quick heal total security2011 instal problem

Hello,



hello
i m unable to install quick heal total security 2011 antivirus second time,its says a demo copy is previously install.please uninstall or buy a new 1.

i have uninstall the older versions , cleaned registries, everthing but no help at all....
but m able to install the older trail versions i.e 2010 of this anitivirus n all other full version softwares.

some expert says dat there r some legacy keys of quick heal total security 2011 when we install 1st time the antivirus ,this keys can be deleted after uninstallation n remains active in the legacy..therefore when we try to install it second time its says uninstall demo version or buy a new 1.......how to delete it if existed...please help