5th gear probs...

Okay, so tonight on my way to my hockey game i was drivin in 5th gear, doin about 85-90 (since i was about 20 minutes late) and all of a sudden it slips out of 5th gear into neutral...sup with that? Any ideas? It happened a total of 4 times on my way there and back. every time i was going between 75-90mph

Turns out my entire tranny was fucked up, bearings, seals, clutch, flywheel. Apparently the tranny fluid plug came out, drained all my fluid and tore the shit outta my tranny. As for the 5th gear, my sincro's went out so yup...$5k later i have my tibby back (no not all for tranny, my timing belt broke and my pistons got to meet my valves...)