error 7100 & plugins and tracks made inactive

[Sharabelle]

HELP! We have Protools HD 3 Accel v 7.3. We've already upgraded plugins, OS, and firmware. We had to replace a defective flexcable between the 2nd and 3rd card. Things were working fine for a couple of days, but now we're getting "error 7100" all the time (as we were before we had the cable replaced), and a cold boot of the computer (as advised in the answerbase) doesn't help. THe current system is using 24 tracks and just over one card. Now a second problem - plug-ins and tracks are automatically being made inactive due to "lack of system resources". We've allocated 90% CPU to ProTools, and are running 24 bit at 96K; we have only begun to use the system so we have plenty of system resources. We are dumbfounded!!!!