AOL Time Warner (NYSE: AOL) just can't get a break. On the day it announces a new pop-up blocking service for America Online members, shares get bounced 5% on a Washington Postreport that the federal investigation into the media conglomerate is widening.

With the stock at around $10 a stub, it's significantly below the company's 52-week high of $27.15.

According to the Post, the Feds may add charges of "aiding and abetting" fraud at other companies to the list of charges it's already considering. Allegedly, former AOL-ers David M. Colburn and Eric Keller struck deals with companies such as Homestore(Nasdaq: HOMS) to help them inflate revenues, both before and after the merger of America Online and Time Warner.

Through an exchange of cash and faked transactions (the practice known as "round-tripping"), AOL may have helped such companies prop up results on a quid pro quo basis. Several Homestore executives pled guilty last year to round-tripping charges.

AOL's name has been floated for a while as the likely suspect that assisted Homestore's round-tripping. The Justice Department, in its investigation of Homestore, said that "a major media company" helped funnel the money back to the online real estate business.

Now, it appears that investigators looking into AOL's accounting practices are also keying in on the company's involvement. This will open a new front in the investigation because it points to the possibility that AOL not only tinkered with its own false revenue numbers, but also helped another company do so. And that could be ugly.

For its part, AOL says it is fully cooperating with the ongoing investigation. Beleaguered shareholders don't have many options here, as they wait for the whole thing to play out.