If your hosting company is having performance problems and your website is down it will have a negative effect on your Google rankings. “If the host is down when Googlebot tries to access your pages, then those pages may disappear from the index until Googlebot can crawl them again.”
Here is information from Google
WEBSITE MONITORING SERVICES
How often does your site go down? Checkout these moitoring services.
Host Tracker
http://host-tracker.com/
Free account monitors 2 URLs in a 30 minute interval and includes weekly reports
SITE UPTIME
http://www.siteuptime.com/
Free account monitors 1 URL in a 30 minute and 60 minute interval and includes monthly reports and email alerts
WEBSITE PLUS
http://www.websitepulse.com/
30 Day Free Trial
DOTCOM MONITOR
http://www.dotcom-monitor.com
30 Day Free Trial
INTERNET SEER
http://www.internetseer.com
30 Day Free Trial
