2001 silverado manual transmission locking up

Hi folks:

I've got an interesting symptom with my '01 Silverado;

every now and again after 2 days of sitting still, I have a tremendously difficult time shifting the vehicle through the gears.

I leave the truck in gear while parked. When it comes time to back the truck down the driveway the shifter is completely seized up, and I must REALLY FORCE it to shift. after a minute of driving and hammering the stick shift into gear it becomes driveable and operates normally.

If if shift the manual transfer case to Neutral, the shifter will operate.

When I attempt to shift the Transfer Case back to 2HI there is a grinding of gears.

truck specs:

hyd. clutch fluid level is normal.

My two chevy dealers in town have heard nothing of this type of symptom. The dealer where I purchased the truck from has only sold 4 manuals since

any ideas?