Problem opening tex files, and rundll32.exe

I find that there are many tex files that I just can't open. I've tried using Slimtex, Tex Resizer and Tex Editor, but they don't work. Examples are Fictional F1 Cars 06,07,08 by someone called Axel180. Also, quite a few of the latest F1 cars tex files. I'm using Windows7 32bit, and have tried all the different compatibility settings and set as administrator, but no joy. Suggestions anyone?
As to rundll32.exe, I did a quick search but there doesn't seem to be any reference to it. So, this is what I've discovered. Frame Rate or P.O. has always been difficult for a great many players that haven't got the latest hardware (me especially). But if you're an offline player, closing down rundll32.exe gives you a massive chunk of CPU back and a much better P.O. number. Step by step:
1. From your Desktop, open your Task Manager window and open the Tab 'Processes. If you've cut your processes to the bone, which you should for gaming, rundll32 should not be there.
2. Start your Gp4, presumably from a shortcut to GPXpatch. Now this is where you and I might differ. On my machine, Gp4 won't start. I Alt+Tab back to Task Manager and there in the processes I can GP4 is running but using 00 CPU. However, rundll32 is using around 40%. So, I RMB on GP4 and end it. Then, restart GP4 via the shortcut and it works. Now, this is where we may rejoin paths.
3. At the first or second menu, Alt+Tab back to Task Manager and observe that rundll pinching all that CPU you need for the game. RMB the bastard and end it.
4. Go back to the game and enjoy that extra boost of CPU.
I'm sure that many of you will already be aware of this stuff, but I haven't seen it written about before.
Finally, in GPXpatch there is the CPU option 'All' '0' and '1'. Mine did CTD a few times using 'All', but in truth I couldn't see any difference no matter which setting I tried.

'Thud! Thud! Is this mike on?' What, no-one got any advice or suggestions?