Immunization reverts back to previous amount

Hi!

I haven't managed to find answers here on elsewhere on the web.

When I do Immunize in Spybot, I get the following result:
Unprotected: 46072
Protected: 154521
Total: 200593

I then proceed to Immunize until it tells me 200593 are protected and 0 are unprotected.
All is fine so far.

... until I Immunize tomorrow or a week from now or a month from now.
Then it will tell me the following:
Unprotected: 46072
Protected: 154521
Total: 200593

I know this because this is the result I get every single time I Immunize. It has been doing this for at least 2-3 months now.
Why doesn't the Immunization "stick"? Why does the amount or immunized objects always revert back to the old amount, instead of saying 200593 Protected?

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Windows XP SP3
Spybot 1.6.2.46
ZoneAlarm 10.2.064.000
AntiVir 12.0.0.1167
Firefox 15.0.1
IE 8.0.6001.18702 (Never use it)
Chrome 21.0.1180.89 (Never use it)