IT'S NOT THE lack of supplies, poor medical attention and unsanitary conditions that are the problem at Walter Reed Army Medical Center.

It's Joan Baez.

Thankfully, the powers that be have solved that one.

In a letter to the Washington Post published yesterday, Baez said the military hospital canceled her appearance there Friday. She had been invited by John Mellencamp to perform with him.

"I have always been an advocate for nonviolence and I have stood as firmly against the Iraq war as I did the Vietnam War 40 years ago," Baez wrote.

"I realize now that I might have contributed to a better welcome home for those soldiers fresh from Vietnam. Maybe that's why I didn't hesitate to accept the invitation to sing for those returning from Iraq and Afghanistan. In the end, four days before the concert, I was not 'approved' by the Army to take part. Strange irony."

Baez told the Post Tuesday by phone that she was not told why she was left off the program by the Army. "There might have been one, there might have been 50 (soldiers) that thought I was a traitor," she said.

Call us crazy, but any soldier who can handle a tour of duty in Iraq can handle a 66-year-old folk singer. And what better way to show how support for the troops has been strong even as support for the war has wavered, than having a peacenik like Baez lead the troops in "Amazing Grace"?

The war is going badly enough, but after "Mission Accomplished," Jessica Lynch and Pat Tillman, could the military please get a new P.R. firm?

The Post reported that Walter Reed officials did not respond to requests for comment Tuesday, but that in an e-mailed statement published Monday on RollingStone.com, spokesman Steve Sanderson said the medical center received the request for participation by Baez just two days before the concert.

"These additional requirements were not in the agreement/contract and would have required a modification," Sanderson told the mag's Web site.

Additional requirements? She plays acoustic guitar.

According to Baez's manager, Mark Spector, that story has holes in it anyway.

He told the Post that Mellencamp's management invited Baez to perform more than a month ago and handled all the arrangements.

Mellencamp earlier told RollingStone.com: "They didn't give me a reason why she couldn't come. We asked why and they said, 'She can't fit here, period.' "

Jorja on our minds

That Jorja Fox is one feisty "CSI." No wonder Grissom loves her.

According to the Star and the New York Post, Fox, who plays Sara Sidle on the hit CBS show, was supposed to bite the Las Vegas desert dust in this season's sweeps finale, but she's refused to show up for work to shoot her death scene.

"Her contract is up and they are in conversations," said Jorja's spokeswoman.

In 2004, Fox and co-star George Eads had a contract dispute and were fired by CBS, then re-hired a few days later.

She reportedly now makes $100,000-per-episode and wants a raise.

Jorja's spokeswoman added that Fox did finally appear on set to shoot her scene but instead of being crushed by a car, her demise is a bit "open ended."

Ah, if that could only be true for all of us.

Tattbits

* TMZ.com reports that Jennifer Esposito ("Crash") filed for divorce Tuesday from husband Bradley Cooper ("Wedding Crashers").

Cooper's rep said the couple has actually "been separated for quite a while."

How long could they have been separated? They got married a whole four months ago, Dec. 30, 2006.

Cooper, you may recall from mentions by our colleague Dan Gross, grew up in Jenkintown and attended Germantown Academy.

* Fortune.com reports that Don Imus has hired Martin Garbus, a top First Amendment lawyer, to battle with CBS Radio over the remaining four years of his recently signed contract.

At stake, about $40 million.

CBS lawyers are, of course, saying Imus was fired for cause. But a Fortune source who read the contract said the deal has a "dog has one bite" clause which may have required CBS to give the I-Man a warning before a pink slip.

* The Japanese distributor of "Babel" is warning audiences the movie may cause nausea or headaches.

Tattle's parents think that warning should come on nearly every movie. *

Daily News wire services contributed to this report.