midi keyboard and vst issue in cubase!

Hey everyone, ive been searching for about a week, but can not find a solution to my problem. Hoping you guys might help

Problem:
I'm making a tune in Cubase, using various vst's, and using my usb midi keyboard to trigger the vsts, nothing complicated, just a simple set-up.

All of a sudden, the vst's (massive, kontakt etc..) stopped detecting the key hits from my keyboard,, although they still detect the rotary controls i have assigned!! and cubase itself detects midi input, Its just the actual keys that wont play anything. the volume on the midi channel moves when i hits keys, but the vsts will not detect or play anything. Although when i play the tune, i can use pitch/mod and rotarys to control and various things on the vst's...
Very weird and annoying! i cannot figure out whats happend.

I have tried re-installing my midi keyboard drivers, to no effect..

Setup

Cubase 5
Alesis Photon X25 midi keyboard
win xp

Thanks, Jez.

Does it play when you draw directly in the midi part?

Hi Shiva! thanks for replying but ive sorted it now. Turned out to be a setting on my keyboard itself, somehow it had changed to some weird program setting and it just needed changing back to default... doh...

Hi Shiva! thanks for replying but ive sorted it now. Turned out to be a setting on my keyboard itself, somehow it had changed to some weird program setting and it just needed changing back to default... doh...