If you are trying to Jailbreak your Apple iPhone 3G 3GS & 4 using the Jailbreakme.com then its better to first read the Steps to Jailbreak Apple iPhone and implement them carefully. There are a few reports that the website when opened and when tapped on slide to jailbreak is getting struck on the Purple Screen and this is in infinite loop as shown below.
Hence first of all you need to stop accessing the website http://jailbreakme.com and access http://jailbreakme.modmyi.com because the original website is getting huge traffic which is the reason the data transfer is getting struck in the middle. If this does not work you will have to make sure that the device is Airplane Mode which was previously mentioned in our steps and also in the above screenshot.
Next try to access the website again and if you are struck at Purple screen or a blank screen then it would mean that there is a error and the installation has to be redone but after clearing and deleting all the cache and temporary data which was transferred to your device through the browser. Perform the following steps.
1) Go to the Settings and Put your iphone to Airplane mode.
2) Go to -> Setting -> safari -> Cookies -> Accept.
3) Double tap home button.
4) Press and hold to Quit safari (in multitask mode)
5) Clear all Cache and cookies from Settings > Safari.
6) Open safari and go to jailbreakme.modmyi.com
7) If cannot, Repeat!
The above steps are applicable mostly for Apple iPhone 3GS & iPhone4 only.