I'm using uTorrentPortable_188.8.131.52260_online.paf.exe stand-alone (i.e. without the "PortableApps.com Suite") on WinXP 32 bit Home Edition, on an account without administrative rights.
Upon "installation" of that version, following "current user" autostart entry is created:
Located: HK_CU:Run, uTorrent
command: "[uTorrentPortable location directory]\uTorrentPortable\App\uTorrent\uTorrent.exe" /MINIMIZED
file: [uTorrentPortable location directory]\uTorrentPortable\App\uTorrent\uTorrent.exe
That causes appearance of a uTorrent installation window on Windows log-on. (Presumably due to its start bypassing uTorrentPortable.exe.)
A portable application should not create any autostart entries. The issue did not exist with the previously used uTorrent version uTorrentPortable_184.108.40.206003_online.paf.exe.