sticking mouse button

using the noise function [thanx for fixing it
] I press LMB for a sec, then move on to a new area. but then usually after about 5-6 clicks the LMB will stick....continually churning the map with noise.
the error box pops up 'LMB already selected' or similar message.
I then have to use ctrl + z to undo mistakes. this gets really frustrating as no matter how slowly I move about the screen, it still happens.
thanx,
jim.

the error box pops up 'LMB already selected' or similar message.
I then have to use ctrl + z to undo mistakes. this gets really frustrating as no matter how slowly I move about the screen, it still happens.
thanx,
jim.