jm..

Thanks for including your operating system. However, some further details might help. For instance, did you first scan with McAfee? The version of which you failed to provide. Did McAfee report a problem?

What provoked you to scan with the (nameless) "Sophos" tool? Was it their Virus Removal Tool which reported Mal/Krap-l? Or another product by Sophos?

Where did Sophos report Mal/Krap-l was located?

Are you experiencing problems? If so, what are they?

In the meantime, did you try scanning with the "Sophos" tool in Safe Mode? Did you also temporarily disable McAfee prior to running the scan?

Without any specific information, I can only suggest to try scanning with the below as a starting point:

ESET's Online Scanner - Their FAQ and Help sections should answer any questions you might have. (Temporarily disable McAfee prior to running the scan)
http://www.eset.com/us/online-scanner

Malwarebytes' Anti-Malware
http://www.malwarebytes.org/products/malwarebytes_free

Keep us informed..
Carol