Windows 7 - Poorly responsive mouse [Dell Inspiron 1721]

Hello !

About two weeks ago, my girlfriend's laptop (Dell Inspiron 1721) running 7 x64 had the mouse poorly responding. Right after the boot, swiping on the touchpad barely moved it on the screen...just inch by inch...
The system loads fine, if I press the Windows key for example it reacts immediately. The same goes if I connect an usb mouse; there, I can move it fine. After a while (from 5 minutes to an hour !) the touchpad will get responsive again.
The problem occurs again when I wake up the system from sleep, although it sometimes doesn't.

So after searching for a program interfering with the mouse, I decided to format the all thing. It seemed to work fine as I was reinstalling everything. Then I decided to apply Windows 7 updates. And bam, at the next reboot, the problem again.
To me, it must be related to a Windows 7 update that messes everything. I really doubt it's a program as I barely reinstalled them, only classic stuffs that are not responsible as they were installed when things were fine (you know, Firefox, Comodo, Ashampoo, etc.). I'm trying to uninstall updates one by one but while uninstalling them does fix the issue, it's there again when I reboot.

What should I do ? I know, I could format again but, if it's probably what I'm going to do, I would like to know if it happened to someone before and if we can identify the issue...

Thanks !

I suggest u to try these apps/driver at the mouse/keyboard section.
Drivers & Downloads

Oops, sorry I should have mentionnied it : it installed those drivers but no luck there...

How old is the laptop?
Nowdays it is not a common problem, but at brand new gadgets, there can be a contact problem inside the laptop. just guessing..
Maybe this contact problem is in connection with the temperature of the laptop, do some work on it to make it busy, then leave it idle for some minutes. See if there is a connection.

Hmmm...weather was pretty hot lately and so was the laptop...that would be a lead yes...will explore this.

What is weird is that it does work after a while...it's just inconsistent.

Thanks !