How to enable SharePoint Library "Open in explorer"

To resolve this please do the following steps.

1) Open the “Service.msc” (Press Windows + R Enter Service.msc)2)  Search “WebClient” -> right click -> Properties -> Set Startup Type Properties to Automatic and start the service
3) Restart the System.
4) Browse SharePoint Library and you should be able to use "Open with explorer" option.

MOSS 2007 sitecollections locked

Well, yesterday morning , none of our MOSS 2007 users were able to do anything on our MOSS 2007 web applications.  I checked my Content DB & Config DB whether it is set to read-only , but it is not. I checked for Quiescing , but it is not.

Finally used control point and , found that all the Site collections were set to read only. Due to the urgency of the situation I executed this script to unlock more than 2000 site collections one by one.
stsadm -o setsitelock -url <URL name> -lock {none | noadditions | readonly | noaccess}

Prior to executing this script, I used stsadm -o enumsites -url <URL name> and stored the url in a file.

Does anyone have a comprehensive script , which can iterate through the Site collections to unlock it , using stsadm? I am now investigating how site collections got locked. Any suggestions?