For the record, in my experience, a Lenovo is the most reliable laptop for audio work.
May I ask what you're using as an audio interface? Do you have a specialist box or are you just relying on the inbuilt Realtek audio chip? If it's the Realtek, it's being controlled by generic drivers in Windows and there's always the risk that, between you two times on Audition, some other programme has grabbed the Windows audio and changed some of the settings. I'd go to the Windows Audio Control panel and, on the Playback tab Advanced options, make sure you're still set to the original sample rate and bit depth....probably "CD Quality 16 bit 44.1kHz". Also, go to the Realtek control panel and make sure that none of the special effects are turned on.
Finally, depending on what you were doing, make sure you don't accidentally have any effects turned on in Audition.