This indicates an attempt to exploit a remote code-execution vulnerability in Microsoft Excel.
The vulnerability is caused by the incorrect processing of a VBA Performance Cache. It may allow a remote attacker to execute arbitrary code via opening a crafted Excel file.
Excel 2000 Service Pack 3
Excel 2002 Service Pack 3
Excel 2003 Service Pack 2
Excel 2003 Service Pack 3
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrades or patches from the vendor: