pear db (installation?) problem

Having installed Pear and the Pear DB package on Windows a number of times (using both go-pear and the pear batch file) I'm persistently getting this error. "Debug Error: c:\php4\pear\DB\common.php line 29 - Class db_common: Cannot inherit from undefined class pear." on the line require_once("db.php"); What's slightly more perplexing is that I installed to c:\php. I've made a complete copy of my php & pear directories to c:\php4 - and tried installing to that directory in the first place but predictably enough this makes no difference. The include path in my php.ini file reads include_path = ".;c:\php\pear" The configuration, as set using pear.bat is bin_dir c:\php doc_dir c:\php4\do ext_dir c:\php\ext master_server pear.php.n password <not set> php_dir c:\php4\pe preferred_state stable username <not set> verbose 1 and c:\php is in my environment path. Please could anyone tell me what I've done wrong or what else I need to do to make this work? Thanks is advance Susie