You might have to take a chance a chance and manually uninstall it through regedit.
Just delete anything that says StyleXP or TGTSoft that is in
HKey_Local_User/Software
HKey_Local_Machine/Software
HKey_Users/HKEY_USERS\
S-1-5-21-796845957-746137067-1060284298-1003/
Software
Then you can search the harder to find ones with Edit\Find