Compilation failed: classes.php Error

I installed WordPress onto my site and when I looked at my site (outside of Maintenance Mode) I found my site had this error,

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in /home/pastel/public_html/wp-includes/classes.php on line 210

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in /home/pastel/public_html/wp-includes/classes.php on line 211

I haven’t done anything to the class files. I have tried multiple layouts, they all have this error. I’m not really sure what to do to fix it.

I have tried deactivating ALL of my plugins as well. That didn’t help either. I have also tried redownloading the wordpress script from the site; didn’t change.

I just don’t know what to do. All my other websites using wordpress work just fine.

Also, I can’t seem to activate the WP-PluginsUsed plugin because I keep getting this error message.

Plugin could not be activated because it triggered a fatal error.

I was able to activate this plugin just fine before. Why won’t it work now?

Can I get some help? I really need it!