If it was by a forum member it wouldn'tve been nearly as permanent - it's not tied in with the forum in any way. The part that's got me confused is I looked at the file in question - it's clearly got the owner's company logo in the corner, which means it was definitely not yours. The company's website also makes it clear that redistribution of any of their files is not allowed.
I also checked with one of the admins higher than me; at this time I'm not currently allowed to disclose the filer of the takedown request, beyond saying it was filed by the company whose rights were violated.
That's literally all there is to it. We cannot unsuspend the account at this time, not when their website says "don't redistribute this," you redistributed it, and the company contacted us to inform us of the violation.
Edit: During my personal investigation into this issue as well, I located another company whose rights were violated. They -also- have a similar disclaimer on their website:
The King Springworks Pty Ltd name, logos, text and graphics are trademarks of King Springworks Pty Ltd and the information is protected by copyright. You may only use the name, logos, text and graphics within this site for your own personal use and can not be reproduced, published in any part for any purpose without written consent of King Springworks Pty Ltd.
This is double-confirmed at this point - just because this -isnt- the company that contacted us doesn't mean we'd allow their rights to be violated too.