How to disable NTFS compression in Windows Server 2003?

I have a Windows Server 2003 R2 Enterprise SP2 machine that is running Oracle 8i. Occasionally, when the server is under a heavy load, it will lock up completely. No operations on the machine are able to be performed and I am forced to hold the power down and perform a "hard" reboot on the machine to bring it back online. A vendor and I are trying to troubleshoot the cause of this issue. The vendor has questioned why some of the Oracle transaction log files are compressed. They asked that I turn off compression for this box. My question: is there a setting or a registry setting that I can change that will shut off compression? Do drives, by default, compress themselves in Server 2003? The only reason that I can come up with for causing the compression is occasionally I will run disk cleanup on the drives which will compress "old" files. I will obviously stop that, but am I missing something else? Any help is appreciated.