This is most commonly caused by packet writing apps such as InCD, DLA or Drag to Disc. Part of the way they work is to keep constant access to the drive so when another burning app needs to gain exclusive access to the drive it can't and the write process will be aborted. If you have any packet writing apps, uninstall them and see if that clears up your problem.
The three main packet writing apps are connected to burning suites.
All three should be found in Windows Add/Remove programs listed under said names :)
If that doesn't work it could also be Windows built in IMAPI burning service which also likes to keep access to the drive. It's a useless app to begin with and even more so when you have dedicated burning software installed.
IMAPI can be disabled by following these steps:
Start >
Control Panel >
Administrative Tools >
Services >
Now scroll down to IMAPI CD-Burning COM Service and double click it.
In the Properties window under the General tab look for the Startup Type drop down menu and select Disabled. Click OK and you're good to go.
If the 'Reason' given is 'Invalid function' (or words to that effect)
You need to update your IDE drivers. Your current ones are old and don't support this IMPORTANT feature.
If the 'Reason' given is 'Access is denied' (or words to that effect)
Another program is currently using the drive. You need to find out what it is and shut it down!
The only way I know of finding out what else has a 'handle' open to the drive is by using Process Explorer from www.sysinternals.com
Load it up and click 'Find' -> 'Find Handle...'
The type 'cdrom' and click 'search'
See if it comes up with any results
If it doesnt, try searching for the drive letter of that drive - i.e. 'F:'
If it finds something, click on it in the search window. The main window should then highlight the process / 'File' entry that contains the handle to the drive. You can right click -> close the handle if you like, or just close the entire application, it's up to you.
You may also get error 'Unknown (34)' sometimes. Cancel the burn, press F5 and then attempt to write it again. It's just windows going mad, nothing to worry about
