Cannot explode region

I get this message when I try to explode a region, it worked up till now, but now with one of the files it displays this message, and I found no explanation about why.

Thanks.

Can you post the file (perhaps with just that Region)?

of course

its larger than 250kb, so I put it here: http://www.2shared.com/file/10091312/ddaf69cb/Drawing3.html

ok, this is funny, I saved it to the dxf, tried to explode it again, it didn't work. But then I closed autocad, reopened the dxf file with the region, then it exploded it without a question.

AutoCAD can be quite temperamental. Good to hear you are up and running again.