Avast! antivirus is active, though windows claims otherwise.

G’day, I’ll attempt to make this as painless as possible.

Computer Information: Dell Inspiron 530, 2.00 GB RAM, 32-bit operating system
Operating System: Windows Vista (Basic)

Today, when I booted my computer, I received a Windows pop-up on the taskbar alerting me that my antivirus was deactivated/turned off. Avast! seemed to be loading rather normally, and when I clicked the notification, in the Windows Security Center, under Malware Protection, it read this: avast! Antivirus reports that it has been turned off. At first, I thought to simply re-activate it, but the problem is it appeared already operational.

I waited for approximately ten minutes, after exiting the warning on the taskbar, and re-checked Windows Security Center. It still claims “avast! Antivirus reports that it has been turned off.”, even though Avast! is fully operational when I open the interface from the taskbar.

Any advice/solutions on this issue? I’m open to all suggestions, but please make all replies relatively simple-to-follow, as my technical terminology leaves a bit to be desired.
I appreciate any and all legitimate replies. God bless all, be it His will, and be safe.

Additional Note:
I’ve included a screenshot of the Windows Security Center dialogue box. Remember, this is what I see, even though Avast! appears to be operational, as I can open the interface and click through available options, etc. I haven’t attempted scanning, or anything of the sort, yet.

Screenshot:
http://imageshack.us/a/img541/8527/windowssecurity.jpg

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