"Failed to upload file."

I get the above error message when I try to upload a file. I have check the logs and there is nothin in them about files. This is the only problem I seem to have with the install. I am running the latest version and have. I have tried the following:

-Looking at the log and found nothing
-Changing the file_storage_provider to mysql
-Uploaded another php page with php upload functionality that worked fine so it is not an obvious permissions problem.
- Talked with my host about the problem and he cannot find anything wrong with the setup or permissions

Any help with this is much appreciated.

Thanks

Brendan

Ilija thanks for your reply. I have been looking over the forums and have tried numerous things to fix the error with no luck. Here is what I have tried:

1 - Turn Debugging on in config - "define('DEBUG', true);"
Nothing happened here still get the vague error message.

2 - Check the log file.
The log file has not picked up the error wich is strange.

3 - I have set up another page with PHP upload to test server permissions.
This worked file an uploaded a file for me but for some reason it is still not working withinn activeCollab.

4 - Change to MySQL provider for files.
Still recieved the same error.


This is very strange behavior and both myself and my host could not find anything wrong with the server so I think it is code but cannot track this one down (I am an ASP person).

Here is what was in the index.php response headers when I looked with FireBug:

Response Headers
Cache-Control no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma no-cache
Content-Type text/html
Expires Thu, 19 Nov 1981 08:52:00 GMT
Server Microsoft-IIS/6.0
X-Powered-By PHP/5.2.2, ASP.NET
Set-Cookie id=1; expires=Thu, 16-Aug-2007 23:10:19 GMT; path=/ token=b7d197f3d964efd58290fb4e53a605fd57a17434; expires=Thu, 16-Aug-2007 23:10:19 GMT; path=/ remember=1; expires=Thu, 16-Aug-2007 23:10:19 GMT; path=/
Date Thu, 02 Aug 2007 23:10:19 GMT
Connection close
Request Headers
Host www.gumpshen.com
User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6
Accept text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language en-gb,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 300
Connection keep-alive
Referer http://www.gumpshen.com/team/index.php?c=files&a=add_file&active_project=1
Cookie token=b7d197f3d964efd58290fb4e53a605fd57a17434; remember=1; id=1; PHPSESSID=9i5v27p381mdjfg2q2111d60q4




Any help with this is really appreciated.

Thanks

Brendan