This indicates an attack attempt against a stack-overflow vulnerability in Microsoft Office PowerPoint viewer.
The vulnerability is caused by an error when the vulnerable software handles a .ppt file that includes a malicious "TextCharsAtom" atom. It may allow remote attackers to execute arbitrary code by sending a crafted PPT file.
Microsoft Office PowerPoint 2003 Service Pack 3
System Compromise: Remote attackers can gain control of vulnerable systems.
Refer to the vendor's web site for the suggested workaround: