i had problems when i jailbreaked my phone with icy. Nothing worked .
My solution i found on the forum .
Quite simply do not select icy when jailbreaking -just select cydia and once jailbreak is complete icy will be on phone.
Just hope you have a 3gs for winterboard because my 3g sufferd lag after i had installed it see post on jailbreak and lag and post your opinion once u are complete with winterboard