Playback random intense noise + can't hear 1 track

Using Audibox usb soundcard interface, randomly a project’s playback will be all intense noise (to the point of ruining headphones). Restarting cubase 5 got rid of it the last time, but not this time around. After 2 restarts the noise is still intense and loud, even after increasing the buffer time.
The laptop has a core i5 monitor and 4gb ram sothe specs aren’t he issue, have played back the same project on lesser specs.

Also in one cubase project, all tracks play back normally except one track for which the midi meter jumps but no sound is heard. Monitoring for it is inactive, its volume level on the track is positive, and again the other midi tracks in the same project can be heard. Can’t for the life of me figure out that one.

Hopefully someone knows the answer to these.