On my old Core 2 Duo Desktop PC with 320 GB HDD and 4 GB RAM, I was originally having Windows XP Prof. and Ubuntu 18.04 on dual boot mode. As Microsoft discontinued support for Windows XP, I erased the complete disk and re-installed Ubuntu 18.04 (Ubuntu 18.04.01 ISO file was downloaded from Ubuntu Site and burned into USB bootable disk). The installation was successful without any glitch. However, when I started to use the system, I noticed that on every alternate boot the system goes into read only mode. This forces me to run ‘fsck’ very frequently. After running fsck the system is fine but upon reboot, it is again goes into read only mode.
In the meantime, I came across article on ‘pop!_os’ from System76. I downloaded the ISO (pop!_os 18.04 non NVIDIA) and replaced my Ubuntu 18.04. The installation was breeze and now my system is stable without any issues.
I would like know why my Ubuntu 18.04 was not successful? Seek comments and guidance.
You could try to use the recovery mode to see if this works. How to do this is explained here.https://wiki.ubuntu.com/RecoveryMode It is possible not anything you have done, just something not right and this is always a good place to start as it will check everything is okay with the install.