Query Error advanced guestbook

Hello everyone,

I've got a mystic problem with the Advanced Guestbook. Everything was OK after installation, but after 9 messages next Error came up:

WHAT TO DO?

Greetings!
Judith, Amsterdam

Query Error
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MySQL Error : Query Error
Error Number: 1 Can't create/write to file '/tmp/#sql3c2_129ee_0.MYI' (Errcode: 13)
Date : Thu, December 11, 2003 16:42:59
IP : 212.78.204.46
Browser : Mozilla/4.0 (compatible; MSIE 6.0; Windows 9

Referer : http://members.lycos.nl/lodemas/vak38/links_01.html
PHP Version : 4.3.2
OS : Linux
Server : Apache/1.3.28 (Unix)
Server Name : members.lycos.nl

It seems the error is gone, I see 11 entries now.