Raj,
Sorry that you are seeing this issue.
Can you please give us some more details?
1. Are you working with a large workspace?
2. Do you have any third party plugins installed?
3. Can you please try increasing the -Xmx value to higher than 768 and see if it works? Try increasing by 100 each time and check if it helps.
4. Can you also check if you can replicate the issue with a new workspace ?
5. If the issue persists, please send us the .log file which is located at workspace dir/.metadata/.log for further investigation. Also share with us the MyEclipse Installation Details from MyEclipse > Installation Summary > Installation Details.
Let us know how it works for you.
–Swapna
MyEclipse Support