Last visits graphs has error SQLSTATE[42000]

After installing piwik for a while,I did not do anything, but the last visits graphs has error:
"Piwik # open source web analytics
SQLSTATE[42000]: Syntax error or access violation: 1064 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 ‘\��-\�aa\�K’)’ at line 3"
I do not know what’s wrong with it.
Please help me, Thank you very much!!

Please upgrade to latest version of Piwik which should resolve the issue

I had updated to 1.4, but it has error: Accident condition! Problem occurred during the request, please try again.
php 5.3.3, mysql 5.1, apache 2.2

The latest version is 1.5.

Thank you ,just now I installed the piwik 1.5, rightnow there is no problem.