9128 6101 errors

[Scotauto]

I a relatively new user of Protools LE8 and with the need to "talk" with other studios I have finally bought the program. I have been looking forward to the system especially the new design etc. (which looks great!" however I have nothing but problems with it. If I run a session with recording etc. there are no problems but as soon as I add a plugin, whether it is from the bundled protools plugins or from my Universal Audio powered plugins there are error messages almost every time, usiually if I try and compare the effect with no effect added (Bypass) With 33 tracks of audio runnig my CPU is max 8%, Disc is 17%, UAD-1 cards are at 2% but still I recieve a message like A CPU overload error has occured (6101) change the buffers etc. When I say OK to the message I can work again until I use the bypass button then the same problem!! If I change the buffer settin to 2048samples I can work for a bought 3 bypass clicks then error message again. If I then change the buffer to 1024samples The audio does not comeout of the speakers although all the meters are moving.. I then have to change the buffers again to start a signal out of the speakers again. This is a big problem. Is it a bug in Protools LE8 that there will come a fix for? (very soon I hope) or do I have to go back to using Cubase which incidentally has absolutely no problems!