Maybe your PC is short of memory. Empty your temporary internet files and recycle bin. Then do a defrag. Also go to start-run and type msconfig in the box. Choose the startup tab and see if too much is being run at startup. Uncheck the boxes you don't need all the time. You could also take a look in OE and if the in and sent boxes have a lot in do a clear out as this has caused me similar trouble in the past.