From: listrecv / gmail.com [mailto:listrecv / gmail.com] 
# I'm getting funny behavior when using irb (readline) on Windows.  When
# I go back to a very long line in the history, I can't edit it.  After
# hit the left arrow a few times, the cursors moves *up* a line, and not
# left anymore.  At that point, I can't figure out what I'm typing, and
# so I have to Ctrl-C.
# Does anyone else experience this problem?  More importantly, 
# is there a
# way to fix it?
# Any ideas or help appreciated.

also experienced that, but when i upgraded to latest one-click, the odd behavior disappeared.

irb(main):003:0> x="athas dfjalsd thsi is a very long line of text asd;fljas;dlf
jas;dlfja;sdlfjas ldjflakj djfkjdf jdkfjsdkfjskdfjksdjf;alskdjflasdjflasjdflasdj
fa;lsdfjalsdkjf jdkfjdkjfkdjfdlksjfslkdjfslkdjfkdjf dkfjkdjfkdjfkd jfl jflskdjfl
aksjdflasdkjflsk djfksjdf klsjdf;lakdsjf sjdflkajsdflksjdflaskjflaskdjf;alsdkfja
;sldkfj;lsd fja;lsd ja;lfk a;ldfj asj;lsdfja;sdlfkj sldkfjslkjfsldjf ;slfjasldjf
a;sdl fasd;lfjs djflskdjf lsdkjf sldjfslkdjf lsf"
=> "athas dfjalsd thsi is a very long line of text asd;fljas;dlfjas;dlfja;sdlfja
s ldjflakj djfkjdf jdkfjsdkfjskdfjksdjf;alskdjflasdjflasjdflasdjfa;lsdfjalsdkjf
jdkfjdkjfkdjfdlksjfslkdjfslkdjfkdjf dkfjkdjfkdjfkd jfl jflskdjflaksjdflasdkjflsk
 djfksjdf klsjdf;lakdsjf sjdflkajsdflksjdflaskjflaskdjf;alsdkfja;sldkfj;lsd fja;
lsd ja;lfk a;ldfj asj;lsdfja;sdlfkj sldkfjslkjfsldjf ;slfjasldjfa;sdl fasd;lfjs
djflskdjf lsdkjf sldjfslkdjf lsf"
irb(main):004:0> quit

C:\Documents and Settings\botp>irb --version
irb 0.9.5(05/04/13)

C:\Documents and Settings\botp>ruby -v
ruby 1.8.4 (2006-04-14) [i386-mswin32]


not sure if this helps though.
kind regards -botp