I have a Sigma 70-210 2.8 APO lens that has stopped autofocusing on my Nikon D2xs. At 210mm, it still focuses but at any other shorter setting will not, just continues to 'hunt'. I sent to Sigma, NY and they cleaned it, and sent back saying parts are not available anymore. Is there any place I can get this problem fixed?

Sigma makes lenses for a variety of cameras. If the lens has Nikon mount then it will fit onto the D5000. However, it's a manual focus lens so naturally you won't get autofocus. The lens also lacks the electronics to communicate with the camera, so you will get no help from the camera's exposure meter and you'll have to shoot in Manual exposure mode.

The "MF" in "Sigma MF 500mm f/7.2 APO" designates the lens as manual focus.

Sounds like the autofocus motor is having issues, I'd suggest contacting Sigma.

go to www.nikon.com/support and ask them, they will answer your question. I have done this before and they are quick to respond

The Nikon D40 does not have an autofocus motor, relying on the lens having one. This Sigma lens does not have such a motor, relying on the camera having one. Nikon designates lenses with an autofocus motor AF-S, Sigma calls theirs HSM.

http://sigmaphoto.com/lenses/lenses_all_details.asp?id=3276&navigator=3

Doesn't look like it.

Yes its a HMS lens it will work on most Nikons

it will mount fine, but I don't believe you will have autofocus.

Unfortunately, this lens is not supported by the D40 due to Nikon's unfortunate decision to leave out the autofocus motor from this camera.  This is why I tell folks not to waste their money on the D40 - access to the many, many, many lenses that Nikon has made over the years, many of which are available used for a substantial savings, is lost on this camera.  The only Nikon lenses that work are AF-S lenses, and some third party lenses that have their own internal motors.  I got a list of Sigma lenses that are compatible with the D40 for you:
The list of compatible Sigma lenses for the Nikon D40 as of the current date is as follows:

• 10-20mm F4-5.6 EX DC
• 12-24mm F4.5-5.6
• 17-35mm F2.8-4 DG
• 50-500mm F4-6.3 DG
• APO 50-150mm F2.8 EX DC HSM
• 70-200mm F2.8 DG MACRO
• 80-400mm F4.5-5.6
• 100-300mm F4 DG
• 120-300mm F2.8 DG
• 300-800mm F5.6 DG
• 14mm F2.8 EX
• 30mm F1.4 EX DC HSM
• 150mm F2.8 EX DG
• 180mm F3.5 EX DG
• 300mm EX DG
• 500mm EX DG
• 800mm f5.6 EX DG

from here:  http://www.imaging-resource.com/NEWS/1177682545.html
Sorry for the bad news.  The cheaper thing at this point may be to sell the D40 and get a D80.  I personally have a D70S, but that is no longer made.  

When you get a flashing EE, it means there is an Eror somewhere. Most cameras have a botton you press to reset it. Usually it is the battery check button. Try that. Also try taking the lens off the camera, unlocking the aperture ring, remount the lens and then lock the aprture ring to the minimum F stop. I think this should solve the problem.