It was installed correctly, I have the vB 4 P Suite, I do have VBSEO installed.
I made the new reg path a few different things but no joy, just redirected to the home page every time...

Works perfectly in Vb 4.2.1 + Vbseo
Compliments!

Short of disabling every single mod besides this one, no not really.

If all mods disabled but this- see if it works. If ti does, re-enable mods 1 by 1 until it stops working.

Well the reason you get sent to the forum homepage is because you have VBSEO. VBSEO does that for any missing page.

Your symptoms therefore are simply that of an incorrect file name. There is no logical reason if you specify xxx.php and have a file called xxx.php it shouldn't work.

Remember file names ARE case sensitive on most servers.

If you go to the URL of the new file directly, does that work? Like http://site.com/xxx.php ? If that works the file name exists and is correct. If it doesn't work the file is not correct or not uploaded to the correct location.

Installed and working on 4.2.1. Voted for MOTM and would highly recommend this mod.

You might want to put a reminder in big bold letters to remember to rename register.php when/if someone upgrades vB. If they forget to do that after an upgrade, they will have problems.

Guys, i change register.php everywhere. but look https://vborg.vbsupport.ru/external/2013/07/33.png
when i click register on main page, nothing change. when i click a have blank screen.

In your Admin CP -> Plugin Manager, Do you have any other modifications that have a plugin on the hook replacement_vars?

If so, temporarily disable those mods and see if anything changes?

We had to install this earlier this week due to having DDOS's all weekend. Since installation, the attacks have stopped and our server hasn't had any issues.

If I understand step 5 correctly, you just want us to open up activateaccount and activateaccount_change and change register.php in 3 places in each file, for a total of 6 edits? Correct?

Thanks :)

Correct

Search your phrases for "register.php" as I found a few other locations to edit aside from the two phrases listed and one is a notice as well. This helped a URLJet client, his register.php page was being hammered and I've been recommending this to others with a similar issue regarding register.php activity.

Tips:
- If you're simply being hammered by spam then another anti-spam mod might be your best bet.
- If your register.php page is being what almost seems like ddos'd (denial of service) with so much activity that its causing issues this mod should help.

Nice idea Joe :D.