IR Receiver on MBP problem

I have a Mid 2010 MBP and have a Dell U3011 monitor connected to it via the Mini DisplayPort output. The problem I have is when the monitor is connected to it then the IR receiver doesn't work on the Mac so I'm unable to use the Apple Remote control!

What's a little odd though is if I point the Remote directly into the receiver and keep it pressed for a few seconds it then picks up the signal and continues to operate okay until the monitor goes to sleep and then wakes up again and then we're back to square one.

The monitor doesn't have a IR receiver so I've no idea what could be causing this issue.

Any ideas, thoughts or help would be greatly appreciated.

p.s. Yep, I've tried changing the battery, run disk permissions, repaired the disk from the startup dvd, run Apple Hardware test from the dvd and generally shut down and restarted everything.