Proactive Threat Protection Is Off

If it was working before, what you can do is right click on client group and select update content.
it worked for me in few cases.
If its on windows serveres it will be Off as per design.

Proactive Threat Protection definitions in the client change to "Waiting for Updates" when running on 64-bit and Server operating systems

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007091713544248

We are going to need a little more info to understand your question. Are you just a client on a larger organization or are you a home user who is running SEP? What OS are you running on and what version of SEP are you using? I am unsure of what specific "error" you mean when you say the proactive threat protection is off error. This could mean multiple things, but here are my guesses at what you might mean.

1. Is this Windows security center that is saying something along the lines of "Symantec endpoint protection is on but is reporting in a format that is no longer supported". If so check this guide http://service1.symantec.com/support/ent-security.....

2. Is proactive threat protection just not starting when the computer starts up? If so you might want to check this guide http://service1.symantec.com/support/ent-security.....

3. Is this a server you are trying to install this on? If so please refer to this guide as to why PTP does not work on servers: http://service1.symantec.com/support/ent-security.....

These are my best guesses at what possibly could be going on. If you could post back with more info I think we could help you easier.

Thanks
Grant