iPhone 3GS losing signal at work

[AshbaHavoc]

This problem has only started in the past 2 weeks. I have trouble sending and receiving text messages whilst at work. No problem anywhere else.

The weird thing is my signal bar never drops. Always on full, and someone else in my office has the same phone and network without any problems.

Has anyone got any ideas on how I could fix it, or what the problem may be?

Thanks in advance.

 

[AshbaHavoc]

Just went out to lunch and got 3 texts that I got sent this morning.

One thing I did notice was I had an "E" next to the signal and "O2 UK" text, and when I'm at work I get a small circle.

Is that something that could be causing the problem?