Great to hear that it works, although I'd be somewhat careful here:
That condition checks if URL is valid and thus removing it could potentially allow non-valid queries into PW which in turn could result in strange behavior and/or security issues. I'm not an expert in this area, though, so I might be worried for no reason -- of course Ryan knows best how this stuff works so I'd ask for his opinion before implementing this "fix".
Most likely better option would be to determine how their rewriterules work and create one that's specific to IdeaWebServer to ensure that URL's still get filtered correctly.
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Somewhat offtopic, I did some research conserning IdeaWebServer and you might want to take a look at this (still unresolved) WordPress ticket: http://core.trac.wor...org/ticket/9763. So clearly there are existing problems with other platforms too.
You did say that WP works now though, so it might be that they've fixed that problem and the ticket was just forgotten.
Anyway, the point of above comment is that if this really is software developed and maintained by one specific service provider, then that's not a very good situation for it's users. But that's naturally just my opinion -- on the other hand it does seem like they've got very good customer service, which always makes things easier.