Unable to access removable hard drive and my mobile as mass storage device

hi frnds i m new on this place as it is my first post..

i m compelled to post because i m facing a serious problem..that is
i m unable to access my new hitacihi portable drive..
as first i connected my drive...
pc showed that... found a new mass storage device..
--found a disk drive..etc etc..
and then showed a symbol to remove drive(or to stop removable drive) in right side of the task bar..
but this drive is not showed in my computer..(as should be like always )
means it is not accessed
i don't no why...
plz help me..how can i access my portable disk
i have tried some more things to make it read like...checking driver property..or the driver cd came with drive(actually this cd contain drivers for win 98. and as for xp.. it says xp automatically recognize it's driver)

and the same thing is with my mobile..( for mobile there is a message dat..device may not working properly, this message comes only in the case of mobile)
i can access my mobile and PDD as storage device through other system but in my system i can't..

my pc's configuration is ...
256 mb ram
845 intel cipset
1.70 Ghz (celron)
OS win xp s2

so plz help me...i m in trouble.. :confused: