I upgraded my server from php4 to php5 after researching and finding that with fully up to date versions it "should just work" and indeed, my gallery, the 2.0.17 board (lightly modded) worked just fine.
My heavily modded board yielded only a white screen and no error logs or anything despite my every attempt to find a reason.
So I used a database backup to build a vanilla phpBB2.0.21 and used the config file from the old board to connect the new install to the existing database...
For me this seemed to work just fine. I was able to log in and post and the redirection had my members getting back onto the site albeit with heaps missing due to the mods being gone - not a bad start for recovery though...
Until I started getting reports that users were having to refresh their pages many times and that MSIE was throwing up page not found errors.
I hadn't had this (Linux/Firefox) and so I used my VM to test MSIE and Firefox in Windows - indeed, MSIE is not loading pages properly - the main index loads but the subsequent pages produce page not found errors but if you go "back" the page you intended to get briefly appears before going to a not found state again!
Your phpBB board URL: http://www.archeli.com.au
Template(s) used: subSilver
Any and all MODs: none
Do you use a port of phpBB: no
Version of phpBB: 2.0.21
Version of PHP: 5
Which database server and version: MySQL5
Host: Debian Stable/Apache
Did someone install this for you/who: no/me
Is this an upgrade/from what to what: sort of - see above
Is this a conversion/from what to what: sort of - see above
Have you searched for your problem: yes
If so, what terms did you try: lots of things from above mostly too generic to get any decent results
State the nature of your problem: MSIE page refresh behaving strangely when following links within the forum
Do you have a test account for us: alltorque/whatever
Thanks for any advice you may have...
In the mean time I am going to be trying to work out how to get the old build fixed for php5.