YACS installation error

YACS 6.9 new install under Apache version 1.3.34 (Unix)and PHP version 4.3.11 MySQL version 4.1.21-standard

Just after clicking "jump to the installation page" this error pops-up "Fatal error: Possible integer overflow in memory allocation (-1024934175 * 1 + 0) in /home/typex/public_html/sitablog/yacs/shared/surfer.php on line 698". I have other instances of YACS running on this host. All started as version 6.x and have been upgraded to 6.9 in the mean time.

Any ideas?

Cheers,

Jan