Unable to start scan.

Windows XP. I ran Avast free once. I want to run it again and I am getting this message - “Unable to start scan. No more endpoints available from the end point mapper”. I do not know what to do, any ideas?

Background
This pc got hit with a nasty virus. I ran Avast with the PC in safe mode and it found 24 viruses. I want to run it again in regular windows mode and I am getting the above error message.

Thanks!

have you tried to restart?

Check for malware with this

Malwarebytes Anti-Malware 1.51. http://filehippo.com/download_malwarebytes_anti_malware/
always update so you have the latest signatures before you scan
click on the remove selected button to quarantine anything found

post the scan log here