I am not on 1.5.8 yet...
-I know, I am too stupid to make the transition.
Hm...
page cannot be displayed, sounds like a problem I had earlier.
I checked stacks of stuff everywhere. And then just by chance I was talking to my Server hoster about it, and he checked Server stuff... and the fault was there!
So of course I smacked his head.
Good idea though first is to
Unpublish any stupid Modules that may cause a conflict somewhere in the meantime, just to be safe.
Like: Banner Rotater etc.
This is demanding resources, but is latent on the site.
It is then smarter to install the Blank HTML module, and actually do such rotations the old-fashioned way, with hard-coded HTML.
At least it works, does that fancy stuff, and avoids using stuff that may conflict.
Just some thoughts.
I will ask my Server dude about the trouble from that side.