First, what do you have fNearDistance= set to? Deadly Reflex 6 recommends you put it at 0 but this will cause menu buttons to disappear in some situations, like in your pics. I suggest you set it to 5 or 6, I use 6. The default is 10, use that if all else fails. I suggest you use 10 for troubleshooting purposes anyway.
Next there is no "special installer" for OBSE and STEAM. OBSE includes an extra
.dll file that you must use with STEAM. The name of the file is
obse_steam_loader.dll and it has to be present in your Oblivion directory, along with the other OBSE files. Below, a direct quote from the OBSE ReadMe.
IF YOU ARE USING THE STEAM VERSION OF OBLIVION:
1. Copy obse_1_2_416.dll, obse_editor_1_2.dll, and obse_steam_loader.dll to your Oblivion directory. This is usually "C:\Program Files\Valve\Steam\SteamApps\common\oblivion".
2. Launch Oblivion via Steam or by running Oblivion.exe. OBSE will automatically be run along with Oblivion when launched. To disable this, rename or move obse_steam_loader.dll. You do not need to use obse_loader.exe unless you are running the editor.
The last sentence about the obse_loader.exe is only relevant if you're using the Construction Set. However you can leave all 4 OBSE files in your Oblivion directory and it won't hurt a thing. I have all 4 there since I frequently use the Construction Set with OBSE enabled.
That's all you need to do, nothing more, nothing less. If the OBSE files are in the proper directory the game will then load with OBSE every time you launch Oblivion from the STEAM Library. No if, and, or buts about it. I've used the STEAM version for a very long time now and know this to be 100% fact. You can verify that OBSE is working because you'll get a small black DOS box in the upper left of your screen when you first launch Oblivion, right before it goes full screen.
With the STEAM version there is no need to launch from anywhere but the STEAM library or right click STEAM down by your clock and select Oblivion from there.
Next possibility for the issue you have is OBGE, Oblivion Graphics Extender. If you run OBGE and AA, Anit-Aliasing, it will cause missing menus occasionally. Below, a direct quote from the FAQ.
Q: The ordering of the objects on the screen is messed up or the game menu has no buttons! Why is this happening?
Q: Once I got the effects to work, my AA disappeared? WHY?!?
A: The method used to expose the information used to read the depth buffer is incompatible with Anti-Aliasing. This is reported to be the case on both ATI and NVIDIA graphics cards, although owners of ATI graphics cards can force AA through ATI Tray Tools without problems. The only solution is to edit the obse.ini file in your My Documents\My Games\Oblivion folder and change this line:
That's it. That's the only three possibilities for this issue outside of an improper Oblivion UI installation. Have you recently changed your UI? (User Interface) If not your solution is above.
I'm willing to bet it's OBGE or you changed fNearDistance=, which the DR 6 installation guide suggests you do, to something lower than the default, which is 10. First change that back to 10 or like I mentioned above, try 5 or 6. If that doesn't work, disable your AA so OBGE functions correctly. Still nothing? Disable OBGE completely by removing the OBGEv2.dll from your OBSE\Plugins\ directory. Report back with your progress.
Good luck.