I guess I should've read his post slower.It does sound like tranny problems, but if the car is stopped, clutch pedal down and it grinds when shifting into first, thats an obvious clutch problem.
Its either your clutch or your first gear synchro's. Mine was doing this because a main bearing on the input shaft went out so the gears were out of alignment but if your synchros are bad it will make it hard to shift into gear and it won't stay in gear like it is supposed to. I ended up just rebuilding my tranny myself and its been great ever since so if you need help just let me know. It ended up being not as hard as I thought it was just a lot of parts. Good Luck!