It does that because it's Fallout 3.
I see that you're not using any of the major mods, so I'll give you a general answer: There are four things you can do:
1. Use Wrye Flash to order the mods and merge a bashed patch. Wrye Flash needs several components and reading. But the bashed patch plus BOSS will serve your needs now and more in the future.
2. Use FO3Edit and Master Update Mode. This requires reading, a 7 step procedure, and a willingness to go through conflicts yourself and decide which mod wins in your patched plugin.
3. Visit the pages from where you downloaded the mods and read the comments section and look for complaints ( not updated to work with 1.7, crashes, bad mesh, requires dlc, incompatible with mod x, etc. )
4. Disable mods one by one to find the culprit(s)