There are thousands of mods out there, but not all of them work together. Oh, and try to use only one mod as a start, and then enable them one by one, maybe it's not steam, but some incompatibility between two mods that's causing your trouble. (If you don't have your CD for some reason, you can also run the 'OblivionLauncher.exe' in your Oblivion folder.
Then, check the box next to 'OblivionReborn.esp' and click OK. Accessing the Firewall menu via the Run box. To enable OR, you need to insert your Oblivion CD and select 'Data Files' from the menu (see image). Next, type ‘control firewall.cpl’ and press Enter to open up the Windows Firewall window. Set both effects for a duration of one second. It installs mods from special compressed archives, OMODs, that allow it to quickly access various details about the contents. Here’s a quick step by step guide on making Oblivion.exe + the Steam executable trusted items in your AV: Open a Run dialog box by pressing Windows key + R. Make sure that you add the Bound Dagger effect first, then add the second bound weapon effect.
I wouldn't worry, Valve is working on getting everything to work right, they already fixed most issues with Morrowind. Not only can you install and organize mods, but also you can organize your load order and implement multiple types of archive invalidation, with ease. a lot of them: more than 28,000 Skyrim mods to download on the Steam Workshop. Try the other mod managers mentioned in the threads. Lots of day Requiem is a great mod for skyrim one of the best mods for. I had the same problem with some of the tools when I used a No-CD fix.
Unfortunately this means most external tools won't work properly (yet). As it seems the Elder Scrolls games themselves work on steam, but the exe files have been changed a bit to remove the DRM.