Final answer:
The corrected sentence should read: 'R2-D2's idea was unusual: sleep all day and work at night when there are no distractions.' The typo (98;) is omitted, the semicolon is replaced with a colon, and 'Sleep' is not capitalized.
Step-by-step explanation:
The sentence '98; R2-D2's idea was unusual; Sleep all day and work at night when there are no distractions.' has punctuation errors. The correct punctuation and capitalization should be: 'R2-D2's idea was unusual: sleep all day and work at night when there are no distractions.'
The number at the beginning is a typo and should be removed, the semicolon should be replaced with a colon as it introduces a list following the main clause, and 'Sleep' should not be capitalized as it continues the sentence after the colon.