I touch the Cydia icon and it starts to load (Displays the black top and bottom borders) and then crashes back to the springboard. Trided doing your solution and it did not correct the issue. (iPhone 2G OS3.01)
Error:
Command 'dpkg -i essential_0-1_iphoneos-arm.deb cydia_1.0.2953-59_iphones-arm.deb; respring ' failed with return code 127 and error message
-sh: line 43: respring: command not found.

Please help!