Your comments
If you can send me one of the comics that has the problem, I'll take a look at it.
The OutOfMemory error is a serious problem as it might affect almost any part of the application.
However I don't know if this is the cause of your problem.
To address it, you can try to allocate more memory to Ubooquity:
The warning is expected when Ubooquity discovers a new directory.
There is a "log" directory in your Ubooquity working directory.
You can also use the "view logs" links in the General settings section (although you will only see the latest lines).
To use this feature, "Folder metadata display" has to be enabled in the advanced options and comics should be grouped by folder (not "flat").
Apart from the name ("folder.jpg" or png or gif), there is no restriction.
My mistake, I'll put it online again and update the tutorial link.
Any error or warning in the logs ?
In the comics and books configuration section, for each directory you share, you have to specify which user is authorized to access it.
If I understand correctly what you did, you created the user but did not authorize any directory for him to see. Hence the empty page.
Customer support service by UserEcho
If the file is not too big (let's say under 10MB), you can try email: tom at vaemendis.net
Otherwise, like you said, you can give me access to your server.
The easiest solution though would probably to upload the file to one a the many free file upload services on the internet.