Panda anti-virus's 12:00PM sig file crashes some of their corporate clients, most of the consumer versions seem to have got by unscathed. I was not so lucky. There fix as of 2:30PM this afternoon was to disable automatic updates, delete the 07/09/2007 12:00PM update and try updating with the 07/08/2007 sig file. This worked for me but was reported to not work consistently. DOH!!!