Two things to try.
1 ) Try going to your start menu, selecting Run, and typing %temp% into it. Then delete the folder called ".buildism" inside of the window that pops up and then try to run Buildism.
2 ) If that doesn't work, try going to Control Panel, selecting Add or Remove Programs, and uninstall Java. Then reinstall Java and see if that fixes it.
1 ) Try going to your start menu, selecting Run, and typing %temp% into it. Then delete the folder called ".buildism" inside of the window that pops up and then try to run Buildism.
2 ) If that doesn't work, try going to Control Panel, selecting Add or Remove Programs, and uninstall Java. Then reinstall Java and see if that fixes it.