For awhile now, I’ve been noticing these blank spaces in my maps. Maybe a plugin conflict? It occurred with 2.38.0. I just upgraged to 2.38.7, and they’re still there. I’ll email you a screenshot.
Hi, from the screenshot it looks like maybe your theme is applying some margin or padding to html img tags (the map is made up of image ’tiles’).
Do you still have the problem if you switch to a standard theme like 2011 for a moment?
If so, please send a URL and I’ll see if I can spot it. You can usually find the CSS using Firebug for Firefox or IE developer tools for Internet Explorer.