set minimum size of Form

how to set the minimum size of a form, which will disable the drag to decrease the size of the form when the form is in minimum size?

Do you want it to remain minimized?

Do you want it to remain minimized?
no, i still want it to resize the form...

You have to subclass the form and intercept the resize messages and block them when they are below your minimums.

i have done this before, but it show's error when i minimize the window

Have you tried this example:
http://www.mvps.org/vbnet/index.html?code/subclass/minmaxinfo.htm