Windows 7: Cursor/mouse button lags

I have an odd issue, that from my knowledge has only started recently. That is that my left mouse button lags quite a bit. This is most notable when i drag windows, as it would randomly select another window under the one i was dragging. Recently, it hasnt been clicking properly, i would have to hold the button down for a shot while (only a very shot moment, but it is very annoying and noticable) for it to click. I have an A4 Tech x7 lasermouse that has been working perfectly for years, it is only in the last few days that this problem has been occuring. I have ran virus scans and checked mouse settings in control panel without success. Any help would be greatly appreciated, thanks.

Given that you said the mouse has "been working perfectly for years" it is possible that the microswitch for the left mouse button is beginning to mechanically fail.

You might not like the answer, but I'm thinking it's time for a new mouse.

I know I've worn a few out over the years.