Gear Grinding? Please Help

my dad has a 98 cavalier, and it has been running great, transmission has had no problems at all. The other day out of nowhere the transmission starts to grind when shifting into second gear (and even downshifting), and sometimes popping out, i drove the car and it seems like its really messed up, i mean almost everytime when going into 2nd it will grind and pop out. Is the transmission going out? it is kind of a high mileage car, or could this be caused by the syncro?if thats how its spelled. Please if anyone could help me out i would appreciate it. Thanks Roy

sounds like something broke in the transmission. but i am not a mechanic but that would be my guess

could be syncro... sounds like it to me... try this... when your driving, and you place it into second gear, c if you can just hold it in second... if you can, it is probly just the syncros, but if it forces itself out of gear, the tranny is probly really messed up (like my s-10's tranny was)... add some tranny fluid and the see if you can hold it in... go from there.......

Grinding and popping out of gear usually means that the dogs on that particular gear are worn/damaged. It's caused by sloppy shifting.
A bent shift fork can also cause this-also cause by sloppy shifting and forcing the trans into a lower gear before it's ready to go there.
There's a set of small raised structures on the side of each gear that fit into similar sized holes in the next gear-These are what "mesh". All the gears in the transmission are always making contact at the teeth at all times, what meshes are the dogs on the sides and this is what you hear grinding when you miss a shift.
If these dogs are beat-they either won't align or they won't stay aligned (popping out of gear).

The only cure is replacement. Sorry to say.