Please help me diagnose a clutch/gearbox problem?

[jameswithers]

2nd gear in my 2002 Boxster S has recently statred to become problematic. Sometimes when I change gear it imediately slips out as soon as I lift the clutch. I find if I want to put it in second I have to release the clutch slowly whilst accelerating slightly. If I try to change in a normal manner it grinds. A couple of times it has actually slipped out of second whilst I have been driving also. It seems more of a problem when changing down than up. I have no issues with any other gear whatsoever, just second gear.

Does anybody know from the symptoms what is the most likely cause of such a problem? I suspect a new clutch but am dreading the possibility there could be a serious problem with my gearbox. I can barely afford the car as it is.