laptop slo slow (boot+10min) but safemode fine

As above, this laptop is running so slowly in normal mode it takes literally 10+ mins to boot fully, and this is even with all start-up apps turned off!! In safe mode it runs alright but I cannot install the apps needed to diagnose what is going on, nor can I run my anti virus program in safe mode. I am trying an online scanner right now but wonder if its a moot point due to the lack of services running and lack of symptoms in safe mode?

I have already run spybot and malwarebytes and ccleaner in safe mode, ccleaner did find some crap but thats about all. I am at a loss about what to do next! I can get a hijackthis log, in safe mode,, but again this does not seem to reflect any of the problems I am encountering in normal modes and I am pretty sure something is running that is gumming up all the resources because everything seems to work,,,,,,,,,,eventually....the only strange thing I found was that when I tried to bring up the task-manager in normal mode it went blank and gave a logon error- failed to create security dialog or something like that..

The machine is like brand new with a brand new memory upgrade to 2gb, running vista in 32bit has intel duo-core chipset.
Please I am at end of my rope after spending whole bunch of hours doing various nothings...I have all the apps I need to run to figure out, or help figure out the problem,, but unable to run or install them!!! what to do next? Thanks, J