Where are all these 'random' shares coming from in my Windows explorer under My Network Places ???

They are automatically culled from your network neighbourhood by the 'netcrawl' functionality of explorer - see: M$ KB, though the article isn't quite correct on reg path it is actually on WindowsXP: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares. Also intriguingly enough Explorer stashes all previously encountered machines at: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\ComputerDescriptions