Bizarre Wireless Mouse & Keyboard issue in SD+

This has got me completely at a loss so any helpful suggestions would be much appreciated. We're running SD+ 7015 and the problem exists on my client machine only (in IE7).

I have a HP NC6400 laptop and a Logitech 660 cordless desktop (wireless mouse and keyboard). Whilst using the equipment with the laptop screen open, everything works as normal in SD+ However, the minute I attach an external screen (Samsung Syncmaster 943n), the mouse and keyboard stutter around (ie. stop / start movement or typing). The thing is, this ONLY occurs when I'm in SD+ in IE7. Absolutely everything else is completely unaffected.

I have tried upgrading all my drivers, check possible interference sources & even running with both monitor and laptop open and still the problem persists. I'm completely stumped. Any ideas? :?: