We try inserting files, editing images and all that.
Everyone has full permissions on the folder.
Could it be something else?
Are the permissions problems for log files written anywhere like to the System Event Log (could not find them there actually)?
Could there be a problem with Windows Vista, UAC, IIS 7 or the fact that application is in a virtual directory?
When we use relative paths for log file path will it search for the subfolder we point to in the plugin folder?

Full permissions for everyone and specifically for NETWORK_SERVICE on all the Logs folder we've found
We've tried a different machine, no result
We also tried to put the application into the web server root (inetpub\wwwroot) - it solved the problems we tried to solve with the URLs, but no logging again. We've enabled full access to everyone to every file and folder on the machine
what about the "general.error_log" setting. Should we care for it?

Full permissions for everyone enabled on everything from the disk root.
Are the source codes available so that we could debug that?
Or you may advise another way of debugging?

We did that explicitly for NETWORK SERVICE, too.
Sorry for bothering, we just really need that working. Very nice tools, wish to use them in our projects...
Little thingies like this make that a bit hard...

No, everything is pretty simple. It's a developer machine under Windows Vista with IIS 7, no domain (active directory), no network shares.
We just added a piece of code to the same application which creates a file in the logs directory and writes to it.
It did it successfully.
So it is not a permission problem.
Could we receive a debug binary which writes such errors to the system log or the source codes?

We do not use impersonation.
We've seen that it used NETWORK SERVICE to create that code-made file (NETWORK SERVICE became the file owner). Does your product use any other account than the ASP.NET application it runs in?
Will that debug build help? Will it give us information on the exception that occurs when writing logs?

Of course we checked the application pool identity
It's network service
If not the debug build, what may help ?

From any programmable part of application we may do ANYTHING to the file system because we've opened everything to network service
We've also just tried creating folders via ImageManager. Everything works fine.
May be a piece of code which creates the log file would help us?

We tried very different options with similar results. We tried (inside of appSettings) like this:

<add key="log.enabled" value="true" />
<add key="log.level" value="debug" />

and like this:

<add key="log.path" value="D:\BG_Redesign\web\Scripts\tiny_mce\plugins\filemanager\logs\" />
<add key="log.enabled" value="true" />
<add key="log.level" value="debug" />

and like this:

<add key="log.path" value="logs" />
<add key="log.enabled" value="true" />
<add key="log.level" value="debug" />

and setting values via session variables.
The same result with every variant.

I can't reproduce the problem, never seen it before so. But since very thing else except logging seems to work you could send me all relevant paths so I can try to figure out it manually how to configure it.

I guess the preview.wwwroot might be: D:\BG_Redesign\web

We turned on auditing on the Logs folder and see no actions - successful or failed. Nothing is trying to write there.