read only issue and slowness browsing lan

Utterly confused about sharing with WIN XP pro ; had trouble with client's
shared Access MDB file on production LAN, set up test bed at home office ;
first time made temp MDB in existing shared directory , got same read only
problem until I played with directory read/write privileges. Then made new
directory and new Access file , and had NO problem opening file - I need
consistent problems or consistent successes .

Also - had debilitating slowness in LAN browsing of same file from SOME XP
boxes - can anyone point me to some info on this ? All clients were in same
workgroup .