empty cd tray ejecting at boot

Hi,

For the second time today, I noticed that the cd tray was open on my early 2008 mac pro, although I didn't remember using it... (The first time it happened, I thought that maybe I hit the eject button without realizing it, but I found it hard to believe the second time...)

I shut it down and turned it on again, and at boot time, the cd tray opened again, (at grey screen, just when the apple is appearing...) and stayed open... (until I manually closed it, of course...)

There is no cd in the drive... and the tray, when open, is asking for trouble, especially as the mac pro sits on the floor...

any idea ?

phjo

Thanks for the hint, as although I didn't hit a mouse button while booting the mac, I just added a new mouse to the mac pro, so it is probably the culprit there...

phjo