Trouble Uploading from Front-End

I'm having trouble uploading a sermon from the front-end. I can from the back-end no problem, but not the front. Every time I get a different error - invalid token, upload error 303, not able to save to the server, and just now "An error occurred...!". I have read every post here that has to do with this topic and tried all the options, but none have worked. I'm not sure what else to try. Any suggestions? I'm on Joomla 2.5.6 and running the newest version of Sermon Speaker.

Thanks!
Tanya

Sorry, just realized I posted this in the wrong category.

I just tried disabling the flash player and using the regular uploader at the top of the screen, but after working for a bit, it redirected me to this page, which was just a white screen...

.../index.php?option=com_sermonspeaker&task=file.upload&tmpl=component&f6a348ed018f0a184370ad0302c24d61=976cdd3096e9bc7e426a78822f5abfdf&8c401496acf162aa2e309a080f1f97b9=1

Tanya wrote: Sorry, just realized I posted this in the wrong category.

Moved to SermonSpeaker 4.x forum

Can you have a look at the error logs if you see something there? Also make sure the target directories are writeable by the webserver.

Thanks...

For the error logs, there are a number of these:
File does not exist: public_html/404.shtml

Other than that, I'm not sure what I'm looking for.

For permissions on the upload folder, it is set to allow the user to write to it, but that's it.