ThinkPad r400 cannot wake up after sleep. A temporary solution is provided.

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I am using R400 25C. The specific process is as follows:

In battery mode, sleep, connect to the power supply, press the FN key to wake up, and find that there is a read hard disk action, it should be awakened, but the screen is black at this time...

This is to press FN + F4 again, sleep again, then press FN again to wake up, OK...

On my machine, I found that the machine could not wake up when the power supply mode is not the same during sleep and wakeup. In addition, it is said that the use of integrated graphics cards will not cause problems...