(Sorry to post in another fellow user's thread, but since this one is already opened...)
I'm also having the same problem with imagebam. It was working just fine and after a manual update (87 new updates!) it stopped working. Maybe it was a coincidence?
I'm using Windows7 64bit, Java version is 1.6.0.29. JDownloader version 0.9.581
The log section concerning the problem:
------------------------ Thread: 17 -----------------------
17 28/01/12 9:22:10 - FINER [java_downloader] -> load plugin: jd.plugins.decrypter.ImageHosterDecrypter
------------------------ Thread: 18 -----------------------
18 28/01/12 9:22:10 - WARNING [java_downloader] -> Imagehoster-Decrypter broken for link:
http://www.imagebam.com/image/f95923150110194
18 28/01/12 9:22:10 - SEVERE [java_downloader] -> Decrypter out of date: jd.plugins.decrypter.ImageHosterDecrypter@1e0338f
18 28/01/12 9:22:10 - SEVERE [java_downloader] -> Decrypter out of date: 15731
------------------------ Thread: 19 -----------------------
19 28/01/12 9:22:54 - WARNING [java_downloader] -> Imagehoster-Decrypter broken for link:
http://www.imagebam.com/image/f95923150110194
19 28/01/12 9:22:54 - SEVERE [java_downloader] -> Decrypter out of date: jd.plugins.decrypter.ImageHosterDecrypter@14b3950
19 28/01/12 9:22:54 - SEVERE [java_downloader] -> Decrypter out of date: 15731
------------------------ Thread: 20 -----------------------
20 28/01/12 9:24:13 - WARNING [java_downloader] -> Imagehoster-Decrypter broken for link:
http://www.imagebam.com/image/e3ec50150491865
20 28/01/12 9:24:13 - SEVERE [java_downloader] -> Decrypter out of date: jd.plugins.decrypter.ImageHosterDecrypter@115e891
20 28/01/12 9:24:13 - SEVERE [java_downloader] -> Decrypter out of date: 15731