Some users who tried to jailbreak iPhone or/and iPad with JailbreakMe have reported that the idevice gets stuck on purple screen and nothing happens. At first thought it seemed that jailbreakMe servers are down, but there is another problem which might cause this problem.
Sometimes iPhone Cache prevents you to access a site. Here is a simple trick to fix this issue.
Step 1: Go to Settings > Safari > Clear History, Clear Cookies, Clear Cache.
Step 2: Reboot your iPhone.
Step 3: Try JailbreakMe.com again and following the steps posted here to jailbrak iPhone 4.
If it still doesn’t work, go through this cleaning process again but this time use http://jailbreakme.modmyi.com instead of JailbreakMe.com.
If this works for you, tell others too.