Virtual Portal and Theme Issue

Hi,
I am having a very weird problem.
I have a virtual portal on which I have applied my theme. This theme folder has an images folder that contains images used for UL.
The image is getting applied on all the portlets in this virtual portal, but the problem is that the log is filling up with the following message:

SRVE0017W: A WebGroup/Virtual Host to handle /images/dot_black.gif has not been defined.

The way it has been defined in the theme specific file is:
.ulStyle{
list-style-image: url(images/dot_black.gif);
text-indent:0px;
...
}

I have tried prefixing the path with a '/' and also with './' but the logs appear the same.

Note: This is happening only on the UNIX box. No problem on a Windows machine.