Same problem -- have cleared the cache & reinstalled
Did everything suggested in Eric's post above... not pretty with all the webassist extensions I own ;-) -- but I persevered... all to no avail. Same error on any site I try. It runs for a while, then throws up this error.
Mac OSX 10.6.3 2.8 GHz 4 GB memory
Guess I'll go now & do my site maps by hand <sigh>