Mass Effect: Glitch or Experience Limit?

My characters stopped recieving experience points.

I have the majority of the game complete, I am doing the last of the side missions before I travel to Virmire.
The Mission I am on is; UNC: Listening Post Alpha
This is when I noticed I wasn't gainin any exp. It's not just the message that stops coming up, I can kill things and then go to 'squad' within the menu and I haven't gained a thing.
I am a Level 43 Vanguard, exp: 153813

It must be a glitch, right? I doubt they would set an exp limit per playthrough, let alone an odd # like 153813.
Any help would be appreciated.

SORTED

turns out for whatever reason, you don't get any exp for killing rachni on the surface of that particular planet on that particular mission. Once you get underground to hives, exp as normal. I found a few others who experienced the same problem.

Thx for responding.