Urgent pelase help. What does this error mean and how do i fix it?

[Drache]

The site has been working fine then this monring when i browse my site suddenly i can't access forums. it got error like this.

Database error in vBulletin 3.0.3:

Invalid SQL: SELECT uploaded, downloaded,ulspeed,dlspeed FROM users WHERE username='C'mere_nemmy'
mysql error: You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'mere_nemmy'' at line 1

mysql error number: 1064

Date: Friday 03rd of September 2004 10:50:04 PM
Script: http://www.mysite.com/forum/memberli...astpostbefore=
Referer: http://www.mysite.com/forum/memberli...astpostbefore=
Username: user1
IP Address: xxx.xxx.xxx.xxx

And when i tried to repair database. there aer 2 tables can not be repaired.

website_db1.cpsession
error : The handler for the table doesn't support check

website_db1.cpsession
error : The handler for the table doesn't support check

And then i have to logout and wait for a while it worked fine again. but after few hrs i recieved datbase error report email saying another member is having this error.

Can anyone please tell me what is going on with my site and how to fix it or prevent it to happen again? i am very worried.

Thanks