I just installed WP 2.9 and then installed the Afterburner theme. When I tried to import the sample content I was presented with a blank page and nothing was imported.
After several tries and no success and after searching the WP forums still with no success I figured I would look at the error logs. I found the following error for each time I tried to import:
[warn] mod_fcgid: stderr: PHP Fatal error: Call to undefined function sys_get_temp_dir() in {path}/wp-content/themes/rt_afterburner_wp/functions.php on line 142
A little more investigation showed that this function doesn't seem to exist in version 2.9.
To resolve I simply edited wp-content/themes/rt_afterburner_wp/functions.php at line 142 and changed the call to get_temp_dir (ie, I removed the sys_ ). That seems to have resolved the problem.
I am posting this here in case anyone else runs into the same problem.