What just started, Rainy? I don't understand what is happening. Please
describe "logging on when idle" more accurately. As a guess, look at
your Display>Screensaver tab and make sure to uncheck the box asking
for a password when resuming from the screensaver.
Check Display> Screensavers and Power Options> Standby for a setting
requiring logon when resuming. Disable settings to get rid of the logon
prompts (or welcome screen depending on how XP is configured).