Yes, I tested and it seems that enabling multi-sites automatically sets pretty permalinks (which is off by default). If I then switch it off, static pages work correctly (eg /page_id=2) as do posts/comments/etc.
I created a secondary blog and it defaults to pretty-links (because multi-sites is already enabled). Both posts and static pages work.
I set the root blog (the one installed by default) back to pretty-links and it seems to work correctly.
I’m going down for dinner in five seconds, but when I get back, I’ll wipe WordPress and see if I can reproduce the error again (or to be more accurate since I already reproduced it several times last week, determine exactly which step fixes the error; eg is it toggling the pretty-links setting or creating a secondary blog?)