vB 4.2.0 db erro

[Termure]

i have a blog post and a new user registered (spambot) and i cannot delete the blog post or the user cause i get db error.
Any1 knows why and how can i solve it ?
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Database error in vBulletin 4.2.0:

Invalid SQL:
UPDATE blog_user SET
tagcloud = 'a:3:{s:4:\"tags\";a:0:{}s:5:\"count\";i:0;s:8:\"dateline\";i:1346842251;}'
WHERE bloguserid =;

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 '' at line 3
Error Number : 1064
Request Date : Wednesday, September 5th 2012 @ 06:50:51 AM
Error Date : Wednesday, September 5th 2012 @ 06:50:55 AM
Script : http://diablo3.ro/entry.php?3-For-instance-a-element-like-moment-heating-could-not-be-as-valuable-for-all-the-ghd
Referrer : http://diablo3.ro/blog_post.php?do=editblog&b=3
IP Address : *myip
Username : GriGore665
Classname : vB_Database
MySQL Version : 5.5.9

[Lynne]

Try deleting the blog post in admincp > vbulletin Blog > blog entries

[Termure]

thanks, solved :) but after deletion blog and user were still there, solved finally with the rebuild everything into mentenance.

thanks again