My guess is you are clearing your private browsing data. Would that be correct? If so, the reason for this problem is detailed in http://code.google.com/p/chromium/issue ... l?id=28788
"There needs to be some way to clear local storage from within Chromium's UI. This needs to happen for mstone 4 per Darin. Let's use the clear browser data box and overload the cookie check box to also clear out local storage. For mstone 5, we'll make things cleaner."
One workaround is to clear cookies using Wrench menu > Options > Under the Hood > Show cookies and website permissions, which will leave your extensions settings intact.
This will be fixed in Chromium 5.x series in http://code.google.com/p/chromium/issue ... l?id=26713