Problem with menu links giving index_1 not index? for new install

[NoviceScotty]

Hi guys - I am totally new to Coppermine, uploaded  Version 1.4.8  followed the instructiosn (or so I thought) and discovered that the menu links didn't work. For example, the link from [Album list] points to index_0.html. A little poking around with the gallery name showed that, for example, the code <a index.php?cat=1 as being converted into index_1.html.

I guess this must be a configuration thing somewhere!?
(I tried changing the character set to ISO-8859-1 which didn't help.)

It (almost) definitely seems to be a coppermine problem, because if I run a test php script with the same echo it works, and I also have a phpnuke site up and running that has no problems with question marks.

I tried replacing ? with &#63; in a few places and the links performed correctly, but I don't really want to do a global replace as I'm sure I've missed something stupidly obvious.

Any suggestions what it is?

[Sami]

Disable SEF (search engine Friendly) plugin

[NoviceScotty]

Great, thanks, that seems to have fixed the problem.
What I had missed was the "use at your own risk" bit in the plug in information. 

[Joachim Müller]

Is in the docs, which are mandatory to read before asking questions. After all, everything is "use at your own risk" - there are no warranties at all.