Error 1004, clean memory?

[Thomas]

High

I use my VBA-code (load data-files, plot data, export diagramms, unload
data and delete diagramm).
After about 30 datasets an error 1004 appears. If I restart with the
30th dataset first everything works fine. Therefore I guess something
like memory overload is the reason.

Does anybody know the error?
Is there any VBA-command to clean memory?

Thanks

Thomas