the easiest way to show us the image is to upload to something like photobucket and then link the file in your post.
as far as your problem - what are your system specs (i.e. how much memory do you have, what kind of video card, etc). it's possible this is just a memory or video glitch of some sort. you might want to start with making sure you're using the latest drivers for your video card. if you don't have quite enough RAM and there are programs in the background that are eating up resources, then it might just be your computer bottle-necking there...
System Information
------------------
Time of this report: 9/17/2008, 15:07:41
Machine name: JOACHIM
Operating System: Windows XP Home Edition (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.070227-2254)
Language: Danish (Regional Setting: Danish)
System Manufacturer: 75D8P
System Model: 775Dual-880Pro
BIOS: Default System BIOS
Processor: Intel(R) Celeron(R) CPU 2.80GHz
Memory: 1024MB RAM
Page File: 558MB used, 1903MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.2180 32bit Unicode
as you can see on my partly copypastet dxdiag i have only 1gb off ram, and i have always got the message

aged pool memory low, after playing about ten minutes ore so, but nothing happens with my game, i can keep playing for hours and hours, without any problems, i have had tf2 since it came out, and have never ever before experienced the prob with the chaticons.
my vidcard is a
RADEON 9250 and yes i have the latest driver for that.
thanks for the advice concerning photobucket, but thinking about it posting the screen off it wont help since i have already descriped the problem.but yeah i deffinetly need more ram, but then again they prob shouldnt write on the box that it only needs 512mbram, i once got the advice that my computer specs should be about 50 percent higher than the minimum requirements to run a game without probs, but guess that is a no go in this case :-(
edit:some off my screens i can see but others are tgafiles, and i cant see those....anybody?