Where can I safetly search domain whois without worrying about the search engine parking on the domain immediately after the search?

I have experienced this myself. When searching for a client's preferred domain name (an unusual one, unlikely to be of interest to anyone else), the domain was available, then 10 minutes later, unavailable! I found an alternative domain, but had to wait the 2 years until the original domain' registration expired before I could claim it for my client.

Instead of using a registrar's search tools, use one of the independent tools out there on the internet. Good examples are http://whois.domaintools.com/ and http://www.whois.net/.

You can also check whois directly using the whois command on Linux (or similar).

I have never had an issue going to the source http://www.whois.net/.

You could also download the Sam Spade software package for free. The software will do a whois for you. Either way I think you are fine.

If you have shell access on a hosting account you can always search from the command line there.