Using 200-500 Tamron on Nikon d300. When I shoot, camera freezes. Clock and exposure readout next to it, on top panel, blink. Camera will not turn off, I have to take the battery out. Lens works fine on D200. All my other lenses work fine on D300. Have been using this lens for several years. Not sure what the problem is.

I know this is a shot in the dark, but have you cleaned the afore-mentioned contacts, both on the lens and the camera, using s clean dry lint-free cloth ?

First, turn the camera off and then remove and reinstall the battery. Turn the camera back on. If the clock and battery icons still appear, try resetting the clock. If this doesn't work, contact Nikon technical support at www.nikon.com and see what they have to say. It may require a repair but determine if the camera is still under warranty. If so, Nikon may repair it at no charge.

This lens lacks the electronics to communicate with the camera. You need to set the aperture to its smallest setting (as you've done) and switch to the manual exposure mode (turn the mode dial to M). You'll get no exposure assistance from the camera's light meter. You can use a separate light meter and/or adjust the exposure by reviewing your pictures.

Unless I'm mistaken, does the camera take the full 12MP when shooting in CH mode? I don't think so and that would explain why you still have 250 exposures left.

I use a cable release on my D300 quite often and in all modes (timed, multiple or single exposures). I am not aware of any special programming or set up requirements. If the release works on one camera and not the other, then you are correct in your diagnosis.
Contact Nikon service. The number and info is on the Nikon web site.
There are two locations. I have had good luck with the El Segundo location.

Setting it to portrait mode should do it. Hold down the shutter button, it should be working. I'm not overly familiar with nikons, but otherwise it'll be in a menu mode if you switch it to a more manual setting. Probably under shooting mode. Set it to continuous shoot

Thats is odd.
When you hook everything up, do you turn on the flash last?
It sounds like the battery pack is giving the flash a different voltage then it should have causing incorrect readings and exposures.
I would send the pack back to Quantum(located in Ronkonkoma, NY) and have them check it.

See second post

likely there's nothing wrong with the D300 - all that's happened is that its inadvertently been set into bracketing mode and hence it cycles through 3 or 5 or 7 different exposures each time it is activated!

on the top of the camera, there is a dial which says QUAL, WB and ISO. Look for button and ring just below this. It should say S, CL, CH, Lv, a clock and Mup. Press the button to release the ring and rotate it to the clock icon to activate self timer