When 3750 was release, I was surprise how small the FLASH was. There are many reason in todays networking world why we need more FLASH to load at least two image (i.e. doing remote upgrade).
Can you do a "show flash" and post the output here?
alternatively, if your logs.text is too big, can you delete it before saving the config? If it's really big, you can configure the log size, else get a syslog server.