check this thread -- seems like there is a problem with the phone.itcl that sometimes goes away if you remove this module (you can just move or delete the file, you don't have to do anything special with it)
one thing i found was that i still get random lockups (less frequently than before) even after removing that file. however, i've been able to fix all of them by pulling up the tivoweb interface on my PC and doing a "full restart" of tivoweb. actually, i've been pretty surprised by how well the full restart seems to work, and i was meaning to post this to a few differnet threads to tell people about it.
the only thing i did notice, is that after one of these lockups and tivoweb restarts, i was unable to access the xplusz scripts thru the phone connection shortcuts. so i rebooted anyway, but at least it was a cleaner reboot than just a power-down.
hope this helps...