Damn these infernal error messages!

I keep getting these error messages in Pro Tools LE 7 during recording/playback telling me that "The operating system held off interupts for too long. If this occurs often, try increasing the 'H/W buffer size'..." blah, blah, blah. If I turn this setting too high I get bad latency which makes playing to and recording with a click track impossible. Right now I have it set too 256 samples and I can rarely get through 10-15 seconds of recording/playback without the error. I've set Processor Scheduling to background services as one website suggested.

Anyone familiar with this problem who can help me out.

Specs: Gateway MX7525 notebook, Athlon Mobile 64 4000+ 2.59ghz, 1 GB DDR RAM, Mbox 2 USB interface, recording to LACIE 250GB external hard drive (Firewire).

Thanks,

Nick