Probably would need more information such as which iPhone model you have, what iOS version, if you are jailbroken, if you cleared all cookies/data/history/other apps in the app switcher, etc.
I have a jailbroken 4s and personally don't have this issue. You can always do a fresh restore.
I have a jailbroken 4S as well, running iOS 5.01. How do I clear cookies/data etc?
Settings -> Safari -> Clear cookies and data / Clear history
Thats right. Any other solutions if this doesn't work?
I'd try that, if it doesn't work I'd clear the app switcher and restart your phone. See if that does the trick.
If it doesn't and you want to restore without losing your jailbreak then there is always iLex Rat. I use it all the time to get a fresh start but keep my jailbreak.
What's iLex Rat?