In many cases , the Cydia application fails to install or update apps after jailbreaking your Iphone with v3.0. There seems to be a conflict with the ICY and Cydia Apps installed on the jailbreak.

To fix:

1.       Backup your phone

2.       Re-jailbreak your phone using redsnow.

3.       Deselect Cydia,

4.       If you’d like ICY installed select ICY

5.       When the jailbreak completes, you should have a working install of ICY and Cydia.