In January 2002, Mustaine was admitted to the hospital to remove a kidney stone. While undergoing treatment, he was administered pain medication, which triggered a relapse. Following his hospital stay, he immediately checked himself into a treatment center in Texas. While at the treatment center, Mustaine suffered a freak injury causing severe nerve damage to his left arm. The injury, induced by falling asleep with his left arm over the back of a chair, caused compression of the radial nerve. He was diagnosed with radial neuropathy, which left him unable to grasp or even make a fist with his left hand (a condition known as Saturday Night Palsy).
On April 3, 2002, Mustaine announced in a press release that he was disbanding Megadeth, officially due to his arm injury. For the next four months, Mustaine underwent intense physical therapy five days a week. Slowly, Mustaine began to play again, but was forced to "re-teach" his left hand.
In order to fulfill contract obligations with Sanctuary Records, Megadeth released a compilation album, Still Alive... and Well? on September 10, 2002. The first half of the album contains live tracks recorded at the Web Theatre in Phoenix, Arizona, on November 17, 2001. The second half of the album contains studio recordings taken from The World Needs a Hero.
Following nearly a year of recovery, including physical and electric shock therapy, Mustaine began work on what was to be his first solo album. The new material was recorded with session musicians Vinnie Colaiuta and Jimmy Sloas in October 2003, but the project was put on hold when Mustaine agreed to remix and remaster Megadeth's eight album back catalog with Capitol Records. Mustaine re-recorded some parts that were lost over time, or altered without his knowledge in the initial mixing process.