A little help please
 

I have encountered this bug where when i open my inventory, it freezes my computer. have any of you had this bug before and know how to fix it?

Bumping for a bit more exposure.

Use a clean client o_o And reinstall Java

ah, that may be where the problem lies, i haven't updated java in aaagess xD
EDIT: I updated java, the cursor doesn't freeze now but the rest of my computer still freezes.

Your comp has serious issues o_o
Java shouldn't be locking up your PC in the first place.

Did you install a clean client?
Usually when minecraft crashes in inventory, is when you have an item you shouldn't have.

just got a fresh minecraft just then, still freezes, this time the cursor did too, and no i don't have an item i shouldn't because i have this problem on all SMP servers and all of my worlds, creative or survival.

Try on another computer. If they work then you need a new computer.