Suddenly no sound for basses or violas in Spotlight strings

[Midiexpert]

I have the latest version of full Kontakt, and have used Spotlight Strings full version for quite while, but haven't used it lately. After some computer issues, today I cannot get the Viola or Bass to provide any sound, even though it is receiving MIDI data. This happens both in Kontakt Standalone and within my host DAW (Sonar Platinum, latest version). The samples are all there, my problems were on my main hard drive, not my sample drive. All the needed files seem to be present, but for some reason two of the instruments are not working.
I'm looking for any guided troubleshooting and/or a fix for this ASAP.

Thanks.