Hatch spacing too dense
Very often, when using the hatch pattern “dots” in AutoCAD, you can be met with the “hatch spacing too dense” error message. It’s infuriating!
The options are to either select a less dense scale for the hatch or to split the hatch area in two smaller areas, hatching each of them separately.
Well, there is no need to compromise on the scale you want or to do any extra work!
You can fix this if you type the following in the command line:
(setenv “MaxHatch” “10000000″)
MaxHatch is an environment variable that determines the maximum number of entities in a hatch area. In the case of the “dots” hatch, if you use a small scale, you will have many dots. If you reach the maximum allowed by your setting, you will get the “hatch spacing too dense” error message.
Luckily, you are able to change the value of this environment variable. Set it to 10000000 and you’ll be sorted 
Additional resources:
AutoCAD 2004 customization tutorial: environment variables http://www.caddigest.com/subjects/autocad/tutorials/select/parsai_environment_variables.htm
Working with environment variables through AutoLISP http://hyperpics.blogs.com/beyond_the_ui/2005/12/working_with_en.html