SAP service starts instances automatically

I am a relative beginner in SAP technology.

I have installed WebAS Java 6.40 on 64 bit Itanium running Windows.

After installation:

whenever I start the SAP instance service using the services panel, the instance starts up automatically with all of its processes even without even executing startsap.exe or starting from SAP MMC. This behavior wasn't there in a previous WebAS Java system installed on an x86 processor.

This is creating problem in my testing. Please let me know how to get over this problem.

Thanks.Raja