Increasing dt reason in disk problem

[shilpasarkar30]

I was running the disk.cpp program and the input file (spherical coordinates) provided in the athena folder.
But if I change the pslope and dslope to the following values:
pslope = -1.0
dslope = -1.5
it does not work. The dt starts increasing abruptly to large values. I am not able to figure out the reason.

** pslope=-1 enforces the disk to be of constant scale height. The scale height is initially supplied through p0/rho0 which is 0.01 (==>H/R=0.1)
** Interestingly I found that if p0/rho0=0.025 (==> H/R=0.05) then it works.
** cs for H/R=0.01 is large, so the dt should become small instead of becoming larger.
** I have used all combinations of solvers etc. but couldn't find out the reason of crashing.

The mesh used is the following (all other values are the same as in the original input file) :

nx1 = 224 x1min = 4.0000000000000000 x1max = 976.8738417239634373 x1rat = 1.0248486311889631 ix1_bc = user ox1_bc = user

nx2 = 128
x2min = 0.0000000000000000
x2max = 3.1415926535897931
ix2_bc = polar_wedge
ox2_bc = polar_wedge

nx3 = 1 # Number of zones in X3-direction
x3min = 0.0 # minimum value of X3
x3max = 6.2831853071795862 # maximum value of X3
ix3_bc = periodic # Inner-X3 boundary condition flag
ox3_bc = periodic # Outer-X3 boundary condition flag