Matlab 2012b startup on Linux extremely slow sometimes.

Normally Matlab starts up in less than 8 seconds. Every once in a while it starts up in about 1 minutes and when that occurs it's painfully slow to use. The system is lightly loaded. You can kill Matlab, launch again, and it's OK. When it's slow the timer option show that the bulk of the time is during "Init Desktop". I have checked the other replies to similar complaints, but none of them were are issue. What is occurring during the "Init Desktop" phase such that we might figure out the issue. Oh, when slow the system is fine and terminal windows are responsive.