Reinstallation Failure

Hi,

I am facing some problems in reinstalling the PCS7 software.
Due to some problem I had to uninstall the PCS 7 s/w from my PC.Now when I am trying to install it again it is failing to open the Simatic Manager.

It gives me an error saying"This application has failed to start because S7acalsx.dll was not found.Re-installing the application may fix this problem."

After uninstalling I tried to delete the Step7 folderunder Program Files\Siemens location but i could not delete it. Is this be a possible cause for the error?

I fear I need to format the C drive to get out of this because reinstalling again and again is not working.

Could anyone pls guide me to get out of this problem?

Thanks in advance.
Duncan.