I have a campaign on the content network, it's been going fine for the past week or so... then all of the sudden today, I have 0 impressions. I checked and no ads are deactivated and there are no notices. Any idea why this could happen?
Did you change the campaign in any way? For example, did you change the destination URL of your ad? If so, your new ad has been taken off line and is awaiting review.
Increasing the bids wouldn't cause a problem. Are you sure that, when viewing the stats, you're looking at the appropriate time range? Check once again that your ads haven't been disapproved. Look in your account and check for ad disapproval or possible account suspension e-mails. Visit the sites that your ads are usually presented on to see if they appear. If you can't find any problems as to why your ads are not being displayed, contact Adwords. That's all I can think of at the moment.
If google truely has stopped traffic, it is probably due to irrelevance or a very low CTR for the pages you are being displayed on. Here is why If your content ad gets a .05% CTR and the top 3 competitors get a .10% - .20% CTR then you are costing google money because you are causing them to get less clicks. Once they have determined your CTR is not in line with other advertisers they will stop showing your ads and keep displaying those with the highest CTR.