This isn't block comment but line comments inserted on each line. Use functionality from the format menu - Add/Remove format (Shift+Ctrl+A) on selected block
If you insist on your "block format" functionality, use PSPad scripting abilities and write simple script what will be applied on selected code -- <http://forum.pspad.com/read.php?2,61268,61269> PSPad freeware editor http://www.pspad.com
