[P/O W. 'Moggy' Cattermole]

What worked for me:

Delete ALL Mat manager files. Uninstall it all. Leave no memories of it!! A pain in the arse, yes, but get rid of the setup.ini, paintschemes/regiments, and also the folder coopreg and anything else mat managery. Anything you are n sure of, leave. Them ai thing is to lose the folders coopreg and regiments.

Now, make a copy of il2fb.exe and rename it to il2.exe
Add the line at the bottom of the section [game]
"ClearCache=0"
also add the line
"clearcache=0" for good measure (one has capitals, one doesn't. I'm not sure which worked, but one of them did, and that's the main thing.)

Now reinstall Mat Manager, if you look on one of the other mat manager threads, there's a link with a unified installer installing all the different versions, up to v2.36, so you don't have to install v2.3, then 2.31... etc.

Once installed, you need to specify the path the the file il2.3x (which should be in C:\Program Files\Ubisoft\IL-2 Sturmovik 1946, or wherever you installed IL2 in the first place to.)

Now load up Mat manager, choose what settings you want. Now, int he centre, find the button save. Click it. Now press the button a little tot he right of it (quit). DO NOT PRESS THE 'X' IN THE TOP RIGHT CORNER!! That clsoes the manaer without loading the new files.

When the manager has finished loading, it will close down. Now load up IL2 and the game should have the new Mats.

This method worked for me, and i've been trying to get the damned thing to work for a while. It is definietly worth it, though!

Good luck!

--edit--

reading another message, i had sound mod, props mod, smoke and trye screech mids, new aircraft etc etc. Loads of mods, and then i installed mat manager. I reckon whether you have nay mods or not makes no difference.