sorry i should have said how to check this ...
go to windows then run type " regedit " hit enter
then go F3 or ctrl+F and type comodo
that will show you the registry key/ keys for comodo
only delete the highlighted key.
" repeat F3 / delete process until it can no longer find comodo"
then your free to reinstall again ..
WARNING!!!
and please do read this ...
playing in your registry area can make unwanted things happen and even stop your pc from working , so please dont mess in there unless you understand exactly what you are doing !