Never seen it on a 3750 assuming the config register is correct . 2948 and cat 4006's we used to see once in awhile . This happened when you got a very quick power hit , actually think it was a code or rommon bug . Below is the brief syntax .
If the switch is power cycled three or more times during the boot process, it will come up in ROM monitor (ROMMON) mode. It is also possible for the configuration to be lost during a failed boot caused by a power failure.
Note:?This problem only occurs on the following switches: WS-C2948G, WS-C4912G, and WS-C4003 with ROMMON versions 4.4(1) or 4.5(1).
During an extreme power outage, where the switch boot process gets interrupted by successive power cycling, the switch will not recover from the third or fourth power sequence and stops at the ROMMON prompt. Typing boot at the ROMMON prompt restores proper operation.
This problem only occurs if the system is reset three or more times in rapid succession while the system is trying to come up. The reported scenario in which this happened was during an extreme power outage, where the power was coming up/down for an extended period of time. If this occurs, you can recover by typing boot at the ROMMON prompt.
Issuing a boot bootflash: will get the switch to continue booting.
This problem has been fixed in 5.5(5) boot PROM (for use with Catalyst OS 5.1(x) to 5.5(x)) and 6.1(4) boot PROM (required only for upgrade to Catalyst OS 7.1(1)), both of which can be upgraded via software. To check the PROM version, type the version command at the ROMMON prompt, or check the "Fw" field in the output of show module command at the console prompt.
Follow the upgrade procedure below.
Upgrading a Catalyst 4000-family product to ROM version 5.5(5)
This document describes the procedure for upgrading the ROM monitor (ROMMON) on Cat4000-based products.
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