It will not be solved by a database restore, as the problem is not content-related. The problem of the messed up layout is caused by the Forums module that generates invalid tables on the on the posts en threads pages. This only becomes apparent in certain skins where Internet Explorer doesn't know how to handle the invalid table rows. Mozzilla browsers have a better way of handling the invalid html and in that case the error is not visible. We have solved the issue ourselve by editing the forum source:

Posts.vb,line 1066, uncomment the statement RenderRowBegin(wr)

Threads.vb, insert a RenderTableEnd(wr) statement in between line 1126 (Next) and line 1127 (RenderCellEnd(wr))

The project team certainly loves tables btw... they are used for every layout scenario possible. Even for generating buttons on a button bar. In most cases there are mutch simpler css constructs possible. Im not a fan of tables since complex nested tables are horrebly slow in Internet Explorer.

It isn't a matter of loving tables, I assure you. It's a matter of receiving the module where the entire UI is generated in the source code using tables. The 5.x version, not started, plans on addressing pretty much only the UI.