If you have same problem, try these procedures:
1) Remove battery
2) Put the battery back (do not switch on)
3) Press Red, Green (actually they are grey because the phone is still switch off) and Camera buttons simutaneously and do not release.
4) Use any available finger to press the power button, so 4 buttons is being pressed
5) Now, screen lights up, then blue logo comes, then the 2 hands finally come back and shake.
But it is not good because:
1) all personalised settings lost
2) all contacts lost
3) some apps will be automatically reinstalled again like nokia music
4) some apps downloaded from ovi store lost
There may be other problems. If you don’t think they are problems, you still can keep using the x6 along with the 4-buttons-hard-reset.

thanks , my phone had similar hang up problem . followed the above mentioned steps and thanks it started working properly. Yes, lost some apps downloaded from ovi store. I think the problem arose as previous night i had downloaded apps from ovi store.
Hi gurmail,
I am glad to hear this tip helped you! 🙂
Heel to all:
I am very boring with this behavior of my X6. Is a nice phone with a lot of good characteristic. But its lack RAM is the most responsible of its bud functioning.
I had must do a hard reset three times losing ALL MY PERSONAL DATA. Now I want another phone.
Just make sure you have updated firmware installed, You can also take benefit of 3rd party applications to improve the performance.